I finally got it!

[kd8cgo]

I just had another thought for your lights if you are still looking for ideas. Maybe you would feel more comfortable tapping into and/or running wiring inside the trailer, in the rear bedroom? You could make "light panels" that would be located in those two rear windows during travel, and stow away when you arrive at your location. A few mating connections inside and you could have a nice clean install without affecting the exterior look of the trailer at all, and gain a good deal of rear visibility while underway... Pretty much the sky is the limit, as those windows give you a lot of surface area to play with.

You might use an inspection camera to check the frame if you don't want to drop the entire belly pan, small holes would be all that's needed to take a look around. They are pretty cheap these days at a place like Harbor Freight. Not sure if insulation batting might be in the way if they installed it underneath...? Also, if you are looking for neat ways to mount A/C - I believe it was Shasta on their reboot model, they mounted a window-type aircon in a lower cabinet, and installed a side vent panel and also vented it through the floor of the trailer, if you are going to be messing with the belly pan like you said. Of course all the ways I have seen A/C installed in teardrops around here, there are no shortage of ideas on that front!