I had been trying to figure out where the wires for the solar panel would go, and my original thought had been to have them go through the roof as close to the battery as possible. That would have left the wires kind of flopping in the wind on the roof though, and I didn't like how that would look. Eventually, I remembered that the roof is made of foam, and I could easily hot-wire a channel in the ceiling from the entry point under the solar panel back to the rear wall, and down to the battery from there.
I felt silly, but even after all this time working with the XPS and expanding foam, I still have to wrap my mind around how easy it is to change things and fix mistakes in the middle of construction!
I drilled a hole through, installed the wires and the waterproof wire thingy, and hot wired a channel back!



It was about this time that I started running out of time, and had to really step things up.
I canvassed the first side, which was a pain.


I started from the top, and was trying to work my way down. Paint ended up getting everywhere, and it wasn't sticking right.
Eventually what I did was to paint a thick coat of primer on the trailer, then stick the canvas to the paint. The paint held the canvas in place, while I peeled the canvas off from the side vertically instead of horizontally. Then painted the trailer again, as well as putting a coat on the canvas.
Then, I smoothed the now wetted canvas back onto the trailer, and used a 4" foam roller to keep working the canvas smooth, checking, rechecking, and triple checking for bubbles. Any time I would find one, I used a hat pin through the canvas to open a little hole, and the roller to get the air out.
After it dried, I used a new blade and cut the canvas at the corner, bottom, and at the edge of the door, giving myself nice crisp seams. I already had overlap from the canvas under the trailer as well as the roof, and I had primed and plastered all the edges smooth multiple times, so I wasn't worried about water.