E-eye-E-eye-Oh........... Hey I like that. I do think your swing-in AC unit would work, but I do agree that the mattress clearance would be a problem, but could be overcome with a bottom-hinged panel, swinging down into the door opening when the AC unit is in the working position. As far as the weight of the unit, I do know that if I had that much weight hanging on my door piano hinge, the whole side of my little woody would bend inward. One solution to this problem would be to install a screw eye in the roof members and tighten a turnbuckle from the top of the AC unit to the roof eye. This would carry the weight while on the road, and be out of the way when parked.
I agree that an AC unit is really nice to have when camping in hot weather, (when shore power is available) and I bring my little Lowes AC unit along whenever I feel I may need it. It's usual location, is cooling my workshop, and when I want to use it in the tear, I place it in the backseat of the car and lower it into the tongue box when we reach the campground. (eliminates unwanted tongue weight).
I have found that the curved scoop for the inlet air, circulates the cool air up across the roof, and doesn't blow across my nose when I am in bed. The exhaust grille in the tongue box takes care of the compressor heat. So far, I have had no problem with water generated by the unit, because it rarely runs long enough, since I am convinced it could freeze ice on the windows.
Roly. ~~ learning that when I roll the new 6ft, 1/4 Nelson Stacker over on it's roof, I must first sweep the floor. Otherwise, any junk on the floor will punch a hole in the 1/8 " roof plywood, requiring a carved mustache patch on the inside to hide my mistakes. (been there, done that) Duh!
Go for it, and take some pics so we can see the finished product.