Re: CHANGED AGAIN! THIS WILL BE IT!!
It took me several days but I finally finished reading the saga of this bus. Well done so far. Can't wait to see it painted, though I suppose that will wait unit spring.
I have a suggestion for the interior panels of your air conditioners. I own an Airstream trailer which also has a curved roof and ceiling, and had ro replace my air conditioner a few years ago. Looks like we both have the same unit, Carrier AirV. I'll try to describe the install but let me know if you want a pic.
The interior "guts" of the unit were able to bolt up snug to the ceiling. Those controls off on the side, the metal flexed enough to conform to the curve. For the inside cover, which has the air grilles and filters, I first made a cardboard template of the ceiling curve, then traced that outline on the front and back ends of the panel. It's tricky because the ends aren't flat but you can get it close enough. Down the long sides I simply connected the low points of the curves, using a straight edge and pencil. The end result for me was that about 1/4" had to be trimmed off the top edge of the long sides. Front and rear ends curved up from 1/4" at the low point to nothing in the center.
For trimming I used a hand held hacksaw blade. The end in my hand wrapped with a rag. It was slow going but considering the expense of the panel I didn't want to risk damaging it by using a saber saw. Final touch-up was done with sand paper. The fit was pretty good but I got some white, self-adhesive weather strip to put on the ceiling to act as a gasket where the panel and ceiling meet. I have seen others use white caulk but I wanted to be able to remove the panel easily, though there has never been a need for that.
Your install will certainly work, but I thought I'd pass this along.