Move to Arizona?

I spent a winter in the Colorado Mountains in an old 5th wheel. You can get electric self adhesive warming pads for holding tanks and a heat tapes for water/sewer lines also this stuff www.gaiam.com/retail/product/56503 is a nice touch on the underside and wrapped on the pipes as is putting a skirt around the rig.

Where I was it would get down to -20F at night and up to 0F in the day - heat wave compared to some parts of Alaska, but nothing froze solid or got damaged.

Wow. I'm from Alaska but I go south for the winter.

When I was younger I did live in a pull-behind and a pick-up camper (w/o the truck LOL) but never had running water. Are you able to be in the same spot all winter? If so I highly recommend piling snow all around/over your RV. Snow is super insulation. When I lived in a little pick-up camper I buried it in snow and I could heat the thing with a few candles or a little propane torch. Space blankets are also awesome, to line the inside and outside of your RV with. Oh, and there are these medical grade water bottles... you can get them at medical supply stores and some camping stores (the bike place in Soldotna has them - Beaver Sports in fbx doesn't) anyways they're super insulative and you can put boiling water in them and take them to bed and they won't burn you and will still be warm in the morning. Always leave your water dripping just a bit to keep it from freezing, and if you have electricity I would go for some heat tape.