Four flat is fine as long as you don't put it in reverse in front of a cop. Most people have no clue what those white lights indicate on the back of the vehicle anyway.
Shouldn't be too difficult to figure out what the heavy red and green wires are for. They do look like they'd either be for charging the house battery, or perhaps one of them is a direct line to the 12V power for the refrigerator.
There should be a power distribution panel somewhere. Gain access to the rear of it, and if there's a big red wire supplying it... There's your answer.
Something that helps immensely is having a portable 12V jumper pack to probe wires and see what lights up. That's how I figured out my camper when I got it. It has a 7-pin socket on the front but it did not follow the standard trailer wiring. When I went to pick it up I had 1 turn signal, running lights, and I think the other turn signal made the CO2 alarm turn on and off.