I put eternabond tape on the roof where the screws are for my solar panel mounts - that should do a decent job of sealing the threads where it penetrates the roof. Also used dicor between the roof and the solar mounts. I also put a generous amount of dicor on top of the stainless screws to keep anything from leaking past the screwheads. Ran the cables from the panels down the refrigerator vent.
There was dead space under the bed that housed the power distribution panel and converter that came with the trailer; I cut two openings in the paneling that covered this area and installed the controller, breakers, shunt, wiring in this area. Then made two cabinet doors and covered the openings I cut out.
Put the meter next to my other switches and idiot meter - that was the hardest thing to do and wire.
My trailer is a 17' foot so is tight on space, not as tight as yours. If you can fit 200A of panel on the roof I think you should do it. I get enough sun in the winter when desert camping. I rarely bring a generator.
