Rick:
I assume you will be unable to check on the coach over the whole winter, so don't worry about checking on the battery water, so long as you use a charger that is multi-stage. The really old ferro-resonant charges would boil a battery dry over the winter if not checked on, but by 2004 I doubt you could even find one in a store, let alone find it as Original Equipment in your Beaver. (My 98 has a multi-stage OEM charger).
For under $100 you can put a very good multi-stage charger on a 15 amp plug, hooked directly to your batteries and never worry. Or you can turn everything else off, including the ELC on your engine, and just use your house charger.