what Jayson m said, I would think if you can spray the main body section you should be able to jamb everything then assemble and spray the outside, it will turn out much better. believe me I've tried this before, It usually just won't work any variance in temp, air flow or the way you shoot it on is going to change the way it looks. a door straight on may look fine but from the front or rear it will be darker or lighter. i'm not saying 100% it can't be done but if you get it right you better go buy some lottery tickets.
Jay D.

I actually rearranged my garage so I should have room now, nice and open. Still kinda crammed but I can work with it.

I will do the jams first, and then assemble and paint. I was wondering, to do this do I mask outside of the vehicle and simply do just the jambs? Might leave a hard line...??

Or do I just mask off the inside of vehicle and spray the jambs and leave be the over spray that made its way to the quarter panel, roof, etc... And just paint over it after I have assembled the car and I'm going to paint the whole vehicle?

What I usually do is jamb it before my final sanding but I will go around the openings with masking paper first 12-16 in out. this makes the final sanding with 600 -800 much easier. if you tape inside the jamb about a 1/4 in. you'll have to look real hard to see the tape line. or you can use the foam tape it works good.
Jay D.