RP-1 RD 107 and 108

[Nich]

I have built some nice rockets in the 40-60t range.  I made a cheap tank 2 type RD 107 at 68t that launches 1.68t LEO cheaper on the 150t pad cheaper then my balloon/balloon 60t version on the 60t pad.  Now I am really struggling to find a good use for these engines on the 150t pad.  I cant not seem to make a good 2 RD-107, 1 RD-108 version of a launcher.  I keep making a first stage that only has 2m20s so the RD108 feels like a waste.  If I under fuel the RD-107s I lose Dv because their TWR is so much better then the RD108s.  It feels like these engines really don't work well until you need 15+ tons to LEO on a 2.5 stage 400t monster.  My 1.5 stage 320t monster can really only put 4-5t into LEO.  I love these engines but I feel like the RP-1 designers put the pad limits at really uncomfortable spots for them.  I would have preferred a 70-80t pad 2 for high orbit contracts, uncrewed flybuys, crewed moon orbit (with some care), 1 and 2 man orbiters, skip pad 3 and go straight to pad 4 at 400-420t for uncrewed moon/mars/venus landings, small stations, possibly maned moon orbit