As far as Winter travel, I have been through Colorado Springs and the Western mountains in January Winter conditions and I never had problems with my water systems freezing. I keep my fresh water tank very close to being filled completely and do not hook up to the water or sewer shore lines except to top off my fresh water tank or empty my sewerage.
Perhaps you can check the rest of the coach and if everything seems fine, then inspect the water system. If you actually need fresh water to get home, then I would fill up the water tank completely, check the pump and faucets, give the seller his money, and hit the road. I would not worry about the water lines as long as you are driving or using the coach. We have been in below zero temps and never had a freezing problem while we were living in the coach and kept the interior temps comfortable. Once you get home, then you can drain the tanks and Winterize the coach again IF you feel it is necessary.