Hi
Everybody does this differently with different goals. To me, having working monitors on the holding tanks would be important. If the tank transmitters break, I think I'd (... uggg ...) figure out how to replace them. Propane tanks don't worry me a lot so I'd let that go.
One totally off the wall approach: Drop in a Victron Venus box.
https://shop.pkys.com/Victron-Venus-...SAAEgLHRfD_BwE
Then do all the control and monitoring via WiFi. I'll even do the tank monitoring .... Welcome to the world of the smart home ... errr ... smart trailer
A more simple approach would be to route the tanks to a SeeLevel panel
https://www.garnetinstruments.com/wp...ison-Chart.pdf
Then do the odds and ends with switches / push buttons. Mount that all on a chunk of plywood and you're done.
Bob