Like what you're doing there. Very sturdy construction throughout.
FWIW, I gutted and restored a travel trailer. The build thread is in my signature line--The Cowboy/Hilton. Maybe you can get a few ideas out of it.
Tips: Insulate everything as best as you can. The good result will be with you forever. My Starcraft is really tight, very little outside noise and easy to heat and cool. I used Low-E windows, sliders. That was a good choice.
Have an electrical layout plan for both 120V AC and 12V DC. I used a couple of junction boxes in the ceiling cavity to make maintenance and upgrades possible. I also installed a 1" conduit in the ceiling to pull future wire, (should it be necessary). All electrical service distribution is initiated in one kitchen cabinet so distribution and service is easy. Locate batteries in the best locations for weight carrying and close in proximity to the distribution. I built my own 12V distribution panel, using switches and bus boxes to ease distribution and control. Inverter and solar charge controller are mounted on this panel.
The biggest and most important requirement with a project of this scope is the schedule and layout of the interior. Having good plans eased the work for me. It's a lot easier to look at a piece of paper and determine the orders of installation than having to go back and remove wall or ceiling panels.