I have no idea of how such a thing could be coded into the game, but I think that custom paint schemes for personal aircraft would add an interesting dimension to the game.
I also rather like the idea of not knowing who is flying which particular aircraft. You really shouldn't know after all, except if you can recognize the specific paint scheme. It is said that there were times when the Red Baron would fly the plain jane aircraft and let his wingman fly the scarlet one, hoping to draw Allied pilots under his guns. Would be very nice to be able to reproduce such a situation.