
My brother, the electrician helped me do my wiring rough-in today. (I'm pretty much clueless.) After looking over my drawings and the fixtures and components that I've already purchased, he came up with a plan, and we made a Depot run.
I reinstalled one of my fir plywood panel and added a piece of 1/4", finished birch to mount the electrical panel to. It will all eventually be the inside of a cabinet.

When I frame out for my ceiling panels, I took a cue from the placement of the factory running light wiring and left a gap for my house wiring. It worked out really well.
There will be a trim piece at the finished wall to ceiling joint that will give me access to the wiring without tearing the whole interior apart.
There will be a second layer of insulation board between the ceiling framing.

We started out with a 100ft roll of stranded 14 gauge (speaker wire) for the low voltage lighting, water pump, and exhaust fan. It took every inch of a second roll to complete the job.
Who'd a thunk?... 200 ft. of wire in a 16 ft. trailer. Plus the 110.
A 20 AMP transformer will provide the 12 volt DC.
My build is based on having shore power hook up. Having been through a few extended outages due to hurricanes, we know how to survive without it.
Without getting too fancy, I will probably, and eventually add the ability to switch my low voltage to battery power, with maybe, even solar charging.
Then again... There's nothing that says "Camping" like the hiss of an old Coleman gas lantern.

Next up... Reinstalling the plywood and mounting the windows.