Since you like bulding your aircraft in wheels-up configuration, have you ever tried Apoxie Clay? In situations where you want to close up the gaps around the doors, without eliminating them completely, Apoxie Clay is great for that. Its a 2 part clay that is water-soluble/workable until it cures. I like to mix up little bits of it, roll it into little ropes, and then work those ropes into gaps with a toothpick. After that, there is no sanding involved. Instead, you use a dampened Q-tip to smooth out the clay and remove any excess around the filled area. Then you can take a damp toothpick and gently engrave nice, even lines into the clay at whatever depth you want. Once you're happy with how it looks, just give it about 24 hours to finish curing and its ready to prime and paint...no putty, sand, repeat dance. There are other water-soluble putties out there, but unlike those, this stuff is extremely strong when its cured, and doesn't become brittle, so it won't ever crack when subjected to flexing or twisting...or an impact, like those times a model slips out of your hands and comes crashing down on the bench top just hard enough to crack putty in a seam which you don't see until you're at the point of putting on decals. 
Hate it when that happens! LOL
Alclad does best with a gloss black or gloss dark blue undercoat, and just so you're aware, its always going to be a fragile finish, no matter what you put underneath it. You can get lots of different tonal variations and sheen variations with it just by how heavy or light you put it on in one area or another. You get the best results by lightly misting it on in multiple passes, and you can vary how many times you go over a particular area to give it an uneven, marbled look if you are shooting for that. You can also layer different colors and sheens of Alclad to get different oxidation and heat staining effects. The stuff is a lot of fun to play around with...gives you a really good way to put some artistic expression into it when trying to re-create a real-world item. Personally, I like to seal my Alclad finishes with AK Gauzy Agent Shine Enhancer. That protects it and keeps it from rubbing off, without causing it to color-shift like most other clearcoats will. You can mist on some flat clear coat after that in the areas you want to look more worn and oxidized. Really makes painting and detailing/weathering aircraft engines a lot of fun and very rewarding.
Sorry about the text wall. I get carried away with details sometimes. 
