This is what I've been working on, a stock-as-usual Voyage-style Duna mission, inspired by seeing @Nittany Tiger, *rseferino from Youtube , @winged and @Chris P. Bacon.
I originally aimed to keep the whole stack under 400 parts, but it looks like my computer will be frying as the MEM alone is 200 parts, and the transfer stage is somewhere around that. Not to mention that I don't have a working Saturn V yet, which will complicate things.
I also aimed to keep the MEM/Hab/CSM stack under 80 tons, but I didn't expect the Hab to be a whopping 60 tons alone, so I have that to deal with as well.
Here's some eyecandy: