It can be easier than that. There are "suitcase" type panels that you can put out next to the trailer and plug into the "solar-on-the-side" SAE-type port that comes on the trailer. Panels are avialble with the controller built in. The controller takes the varying-voltage enrgy from the panels (e.g., clouds) and gives a steady 13V supply out the wire (at varying amperage) to charge the batteries.
The system i use is from "ACOPOWER" (https://smile.amazon.com/ACOPOWER-Po.../dp/B07D4PHKLP
). The suitcase type panels are all exactly the same, likely made in china and re-branded, so you can go based on "is there a controller included" and price. Way cheaper than a rooftop/permanent insall, and you get the the flexibility of putting the panels in the sun if you're parked in the shade (you can get extension cord also). Downside is somebody can run off with them, but so far so good here with a bike lock through the handle.
We've camped for 4 or 5 days and had basically 2 full batteries when we left off the 100W system, but of course YMMV based on how much yuou use (mostly the heater fan) and how sunny it is.
But don't be scared, you can either go this simple route, or pay somebody to hook it all up for you with a beefier system for more money. But either way will be easier, quieter, and safer than a generator (no gas, no noise, can run all day regardless of if you're there, etc...)