Well George, I do appreciate your input, even it was so negative. I love it when I am told that something CAN'T be done, it just reinforces my resolve that, yes, there is a way to make it work, and I will do my damnedest to make it happen. I guess I am one of those people who "has planed up a door to fit, and no what you mean", as I was the official company door hanger for years, when I worked at the trade, and probably have over 500 hung doors under my belt.
You may have misunderstood my hinged panel extension on the door, below the AC unit. If it were hinged to flip outwards, it could lip over the outsides of the tear, and weatherstripping would provide water protection. It would be flipped up first, then inner door panel swung in with the AC unit attached. A radius to match the arc/swing of the door would have to be provided at the latch edge of the unit, no problem.
Then installing a rigid, removable carrier beam, such as an oak 3 x 3 or some such timber, could be rigged near the roof to provide for the up and down movement as well as any fore, aft, and side to side motion . Door jamb members could be made proportionately heavier and the AC unit hung on morticed, ball-bearing hinges. I've used them for supporting 400 lb leaded x-ray room doors, so should find the mere weight of a small AC unit to evince no concern. Furthermore, the top corner of the latch edge could also be secured rigidly to the roof beam, supporting 1/2 of the weight and to provide side to side stability, as in a structural shear panel.
I understand that you feel that some of my ideas are "no good" and I know my suggested solutions seem a little overboard, especially when you consider the proposed X-bracing cables that are tightened with turnbuckles inside of the tear. The cables connect to eye-bolts at the roof and just above the mattress, creating no structural problems for the sidewalls or floor.
So, "straining the tears floor and destroying the ceiling and eventually weakening the sides" may not be entirely accurate. Sorry that you feel that this idea is a "none starter", but difficult and impossible have different meanings. Personally, I wouldn't consider positioning an AC unit this way, as I am so content with my removable AC unit placed in the tongue box when camped, I just happen to think it can be done.
Please take these comments tongue-in-cheek, just as I did yours.
Roly ~~