Thanks for the suggestions so far!
Judging by the replies the indoor/outdoor question was silly. In my own defense, I'm an aircraft mechanic and you'd be surprised what we can do on the ramp. Also, all of my references show the aircraft being maintained outdoors. I can't find a picture of a hangered bird.
So I think I'll build a partial hanger, two walls forming a corner and the floor. One problem solved.
Thinking about how I would do the modification if it were me, I would do all the mods first, then paint it last. So I guess I'm leaning towards 17thBG markings.
So far I like stingers suggestion of a play on the word Doolittle. Now too just find the right combination for a real snappy title.
Thanks
Darren