I use my coach in the winter and head to Florida in January. I just got back from a family trip at Thanksgiving and the temps got into the mid 20's at night. No problem at all with the coach while we are staying in it because my plumbing and tank bays are heated. I put in a 70 watt bulb in the dump tank bay just to be safe. Once we get home, I just blow out the lines (takes about 10 minutes) and plug in leaving the heat at about 55 degrees. Of course I dumped the tanks after the last use.
My coach has an air chuck and I made a simple device with a pressure regulator and an old garden hose that I keep in the bay...when I get home, I hook it up to the fresh water hose set the pressure at 40-60 psi and blow out all the lines. I dump about 1 gallon of anti freeze in all the traps and toilet and open the black and grey tank valves so the antifreeze will go in to the macerator so it doesn't freeze up.
We are using our coach again around Christmas for a few days and then back in the pole barn till we leave for Florida in January.
Jim, MJ & Spirit Bear
2005 Prevost Royale, XLII
Jeep Wrangler Sahara...toad