On the few occasions we've winterized the coach while staying at our Adirondack cottage through the Christmas/New Years holidays (most of the time we stay in the coach), we de-winterize a day or two before we head south, fill the water tank, and just keep the heat on until we reach warmer weather for our own comfort. We've never had a serious problem with frozen water lines even at sub-zero temps. If there's still a few below freezing nights when we come back for spring clean-up, it doesn't matter since we'll have the heat on anyway, but I could blow the lines out if needed.
