I remember that episode where the guy did have a tank. That was very err odd, but funny. You've got to think, where'd he get that...
He got it from a local Army National Guard armory, it was an M-60A3. I'll put up a link for the whole story below, in case someone here never got to learn the full story.
http://www.signonsandiego.com/news/nation/19950518-167-stolen57.htmlPretty much, GuiltyRoachKillar had the right idea on how it could work. It would be similar to the spray shops in GTA, where you pull your car in and the door closes. A few seconds later, door opens again and your car is fully repaired and repainted. But he also mentioned the technique to do it. You would need a model for every paint scheme you wanted. I have seen it discussed where someone used a "setObjectTexture" command. But that starts getting pretty complicated.
I don't think this will be too difficult for you guys to work out a solution, sounds like an interesting idea for some of those civvy or non-combat missions. Good luck with it.