I would definitely go with your second plan of running the controller in the cabinet.
Knowing Nash, your trailer is solar ready and you should have a closed in area in one of the cabinets, possibly near the control center or sometimes near a main switch panel where the factory has intended a controller to be mounted.
We have 260 watts on our roof with a 20A mppt controller, 2 225ah 6v batteries and a 1500w inverter. Keeps our trailer powered nicely being somewhat power conscious.... We also carry a gen as a backup, the sun is not always available in many of the sites we go to. I am considering 4 batteries as well, but only because we camp for extended periods off grid and like to occasionally use the coffee pot and or microwave with the inverter, which is extremely hard on the batteries.