I dunno about the whole "smart Airstream" thing. The more effort you put into installing marginally useful doo-dads, the more time you will spend trying to fix them when they inevitably go wrong. Most of this stuff wasn't designed for the harsh environment of temperature and motion extremes that exist in RVs.
Remember, "The Price of Recreation is Eternal Maintenance"
Lighting-wise, I'm a fan of the 12V
LED pucks, myself. There are two types of lights necessary in your Airstream- overall dispersion and focused task lighting. I don't think that having all of those down lights in the center area is going to do much, that's where some dispersion lights (like the stock ceiling lights) should be. The pucks are good for over the galley countertop and stove, and larger downlights work well over the dinner table. You can also get good dispersion by aiming a downlight up, and firing it across the curved wall/ceiling. Very dramatic! Being able to turn on a few small lights uses far less power than always turning on the big ones.
I like these round toggle switches: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
You just drill a 3/4" hole, rather than try to make perfect little square holes. Use stranded wire that's both color-coded and labeled at both ends.
My yachty friend, Capt. Z, sent me a link for a battery monitor that looks good: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1