Sorry for delay in replying... As I understand it, 2 6-volt deep cycle batteries will provide power for a much longer period of time than 2 standard 12-volt batteries. The battery dealer said to me... just feel the weight of a 6 volt vs. 12 volt battery. The extra batteries are in series with the existing batteries, so they are charged along with them. I have not worked on covering them - not sure a cover is really needed though - e.g., the chassis battery isn't covered. After 1 trip to Burning Man on miles of a dusty road, the batteries were covered with dust, but work fine - not pretty, but who cares? Here's a link to another post of mine: http://www.forestriverforums.com/for....html#poststop
I'm thinking about solar, but so far haven't made the jump - that's probably another $800-1,000.