Cunjo Carl

@Spaced Out Mun's a tricky one! There's precious little flat ground, and it's very difficult to tell from orbit how slopey your landing site will be. The good news is there's a half-dozen solutions, but none of them are magic bullets. Hopefully they'll give you a starting point for thoughts on new designs! Also, unless you have a play-style reason against, I'd say don't be afraid to test your craft ideas in a sandbox mode with cheats to get a feel for things. Making the idea-design-test-result cycle quicker can make a surprisingly big impact.
No-tip lander options
1. Scout ahead. Send out comsats and rovers to scout out landing sites in advance. Finding flat-ish ground can really make all the difference
2. Broaden the leg-base of your lander. Depending on the size of your craft, you can replace taller fuel tanks with a few more stout tanks attached radially near the bottom. You can then put legs on these to make a squat, stout craft which will stay upright even on the steep slopes. These tanks will typically need aerodynamic cones for launch, but you can place your legs directly on these cones, so it's generally not a big deal during construction.
3. Increase springs on legs. If you're on a slantly slope, a higher spring constant will keep your rocket more orthogonal to the surface, rather than sagging downhill and tipping off balance. They also make you sproing off the surface like a super ball when you're trying to land, but you can't win 'em all!
4. Add tons of maneuvering. With enough reaction wheels (anywhere) or manuevering jets near your rocket top, you can just let your rocket lay flat to land and then sit up off the surface when you're ready to go. This works better on smaller, stouter craft, where the 1.25m reaction wheel really works lovely for its size, and the torque required isn't too vast. On larger craft, a couple jettisonable twitches near the top can serve a similar role.
5. Use airplane landing gear rather than legs. They naturally stick out, rather than almost straight down so it's much easier to get a broad base with them! Just make sure to account for the added weight, and pull them out of the tank like they want to be when you first place them. It looks a little silly, but it works nicely. Don't forget to apply the brakes!
6. Go to Minmus instead. *cough* It's got lots of nice flat places for easy landing, and is generally a much nicer trip. It's harder to get into its SOI, though.
 
Reentry from Mun options
1. Multi-pass through the upper atmosphere ~35-45km. This will bleed off the speed slowly, and create less heating all at once. The downside, of course, is it'll bleed off the speed slowly. I tend to put my final pass in the 22-28km altitude ballpark.
2. Lots of empty fuel tanks can help slow you down if your trajectory isn't too steep; this works well with the multi-pass. In this case, it's best to fly 'broad side of the barn' style to catch all the wind you can to slow down. For this, make sure to bring plenty of batteries, or have a way to recharge between passes (solar panels). Especially in this case, you can use body lift from your craft to control your trajectory. Making your craft a front-slash into the wind will make it lift up.
3. Retro-boost before entering the atmosphere. By bleeding off a few hundred m/s, you can often make easy work of an otherwise tricky reentry, or save yourself a couple passes. It wastes deltaV of course! If you happen to have extra fuel in the tanks, I'd say no harm done.
3. Use heat shields. In this case, you wouldn't so-much need to use them for their ablator, but instead for their high thermal tolerance. By removing most of their ablator, you can reduce their impact on your deltaV budget. The downside of the heat shields is they're very slippy aerodynamically, so you won't get much upper-atmosphere slowing with them. This can actually turn into a downside.
4. Put your kerbal in the service bay... There, I said it! Command chairs in service bays are so effective at reentry, that many consider them cheaty. I consider it funny! To be honest, it's probably best to avoid this for your first journey, but be aware that it exists.
5. Use fins as makeshift airbrakes. While this doesn't work with basic fins, structural D wings can be used as makeshift airbrakes from Mun return velocities. It's considerably more difficult than the other options, though.
6. If you're in the lower atmosphere but lawn-darting down to Kerbin, you often have a better chance of survival out of the craft than in. Bail! This will always work over water, and works maybe half of the time over land.
 
 It's KSP, so there's of course other options for all these, too. Hopefully something sounds fun and useful for your case. Best of luck! Let us know how it goes.
edit: woops, didn't notice others posted while I was typing in little bits here and there.
You can post images by:
1. Press the Print Screen button (or your computer's equivalent) while looking at your craft in KSP.
2. Alt-tab out and open Paint (or your computer's equivalent). In paint, press ctrl+v to paste in the photo.
3. Save it as a jpg.
4. Go to an image hosting service (imgur is this board's favorite, but I like Postimage for its simplicity)
5. Upload your photo to this site, and it'll provide you a link.
6. Paste that link into your post, and it'll appear as a photo like magic!

Maybe I finally got it? It might all be correct after all, and I was just looking for a decay-to-zero that was way farther out there than I expected. I just realized that if we're plotting efficiency relative to a logarithmic mass ratio, the value actually shouldn't decline very quickly. We should only be able to see the decline on an exponential scale, so I replotted in terms of one, and got something I'd really like to believe!
 
 
It seems to be working out, but I'd still love a second set of eyes on all this. If the urge to take on some math strikes anyone, some corroboration (or rebuttal) would be hugely appreciated.. Otherwise I'll probably mark it as solved in a few days.

@JacobJHC
I can't speak from personal experience, but @Turbo pumped was known for some insane optimizations along these lines, and has a Moho run which shows off the maneuver you're planning. I'll put the youtube video in the spoiler... looks like 15ish degrees. Also don't forget you can plane change at Eve if you happen to find a Kerbin->Eve arrival time near a Eve->Moho leaving time on a transfer calculator. Just at a glance, I'm finding
Place    yr x day
Kerbin   8x207
Eve       9x42
Moho    9x143
50 Kerbals to Moho!? Sounds like a heck of a trip.
 

Absolutely not in there at all. I'm about to fix that in 10 minutes though . Structural fuselages are pretty standard for this roll, but I'm hoping there will be another thing that pops out when I start poking around.
 
Edit: The results are in! The structural fuselage has always been the part to beat for 1.25m floatation, and it was a tough bar to beat! The best float for the mass was a closed klaw. Unfortunately, they only have one attachment node and they're very draggy, so perhaps not of much use for a katamaran.
Along those lines, the big strakes didn't come in that far behind the structural fuselage, and they're very low drag (they use the lifting surface model rather than the drag cube model). They also reenter more easily than fuel tanks or structural fuselages. I might give those a look!
The mk1 diverterless intake and mk1 engine nacelles also had floatation/mass similar to the structural fuselage, but substantially better float/length. If you wanted a shorter hull with more stuff on it.
The most important collumns are the mass, and the EW/mass, which describes how many tons a single ton of that item can hold afloat.

Again, best of luck @Avera9eJoe! Let me know if there's any other parts in specific you'd like tested and take care on the journey to Laythe. The last step is a doozie!

As an avid vernor aficionado, I can attest this is a constant problem. Generally, I get by with attaching them to any available surface such as adapters or literally any radial rigging. When doubt, if you're trying to vernor a dead cylinder like this Sr. docking + poodle fuel depot, you can make your own little hard points out of basic fins or radial decouplers. These can be placed anywhere, but for aesthetics I tend to put them near the base.
Because pictures were encouraged, here's some large but highly compressed jpgs to show the idea:
Good luck and have fun with one fewer resource to worry about, @WanderingKid!
 
Edit: Just discovered the little landing gear can be used to make a handsome little place-anywhere-5-way-rcs-port for vernors. It may weight half a ton, but look- It's so cute! (Steering the wheel doesn't move the vernors, sadly. Steering can be disabled to prevent it from looking silly however.)

 
Edit edit: Last time I swear! I keep thinking of new ideas 2 minutes after posting. This setup is probably the simplest solution... Two-way and four-way place-anywhere-rcs-blocks can be made using a cubic strut. Given how often I've faced this problem, how I never considered using a mini strut until now is anyone's guess. It's not the nicest looking of the options, but it sure was easy to make. A picture is enclosed:
 

@Jestersage This depends a lot on your desired launch profile. Steep profiles care more about TWR (in conjunction with low drymass as in your case) and shallow ones care more about drag (specifically Lift/Drag). I agree with @Foxster that on Kerbin, the difference shouldn't be too severe. As a rule of thumb, minimizing the number of stacks is typically best for space planes, but the best way to tell is probably just to try! (or send us a picture and we can hmm and hah.) Also, if you'd like me to foist the governing equations at you (and the thoughts that govern them) let me know.