For such a small level of use I would think that 200w on the roof and a few batteries in the bank would have you good to go pretty much forever.
Going on bank alone is very doable at low levels. With no high power inverter loads I would think a pair of golf cart batteries would be a good choice. You will need to have them connected to the truck systems or have a generator for when they do need to be brought back up with out hook ups.
Higher voltage for less drop is a good idea for a portable but I can tell you that if you move often, a big panel would get to be a hassle fast. You can get the higher voltage desired by running a hinged pair of smaller panels in series.