Math/Science Guy

I'd first land a rover compatible with a common base for all your modules so you can connect them. That is what I did for my base. Still a work in progress tho.

I'd put on some reaction wheels and RCS of course! Also make sure you got some air brakes. For me, I made something like the Falcon 9. The booster usually expends it's intended selected fuel for ascent at about 14,000m. From there, I don't have to worry too much about thermal damage and use selected fuel for decent later.