I rewired my travel trailer, both 120V AC and 12v DC. I'd suggest to break out a piece of paper and mark locations for all receptacles, lights, pump, fans, and any 12V jacks needed.
The 120V is straight forward, observe typical residential code and you'll do fine.
For the 12V, you'll be able to do something that typical RV mfgs don't--pull both a positive phase and negative phase wire for each 12V device location instead of using a frame ground. This greatly eliminates a lot of 12V problems in the future.
I also pulled both supplies up into the ceiling and dropped down into the walls to the locations. I used 4" junction boxes in the ceiling so diagnosing a problem in the future is easier. I covered the hole for the junction box area with an aluminum plate that serves as the mount for a dual light fixture. I also installed a vacant 1" conduit in the ceiling, leading aft. That is for any future upgrades in the rear.
Good luck with the wire !