Astro turf cleans super easy! You can clean with a garden hose if you want or if you don't want to get everything wet then just vacuum it and once in a while when it gets really dirty shampoo it like a regular carpet.

Slight angle does not work well for aerodynamics on trailers - its always recommend to go flat, unless you hinge them down on one side and create prop bars on the other to prop up when not moving.

Dump the idea of 6volt! its not necessary for your application. 12volt deep cycle batteries will do just fine! Convert everything to 12volt dc, throw away the ac/dc inverter, they just waste energy and create heat! You probably only need two 150amp cells anyway unless you are planning running an induction cooktop instead of a propane(I recommend propane - a little lasts sooo long) I also recommend a propane fridge costs a little more, but worth it. Heating I would cut out a hole in the top of your camper and install a little wood burning fireplace and if your in the cities than use propane heat. With panels, the power output will simply not be enough to heat you when its cold. For cooling - Try to park in the shade and if you are in death valley then your panels may be enough in the day time to give you ac for most of the day. If you are trying to go ultra green than you can make your own Hydrogen from water with your panels as you drive, but thats another topic..