I suspect you may have more issues pulling a Trailer verses driving a Motohome contained heat system. The on-board heater setup vents hot air to all the places that might be effected by cold weather freezing temps...
I imagine some folks may do some winterizing for the trip until they get to a warmer climate zone.
In my case with my small footprint OFF-ROAD POPUP trailer setup it is very easy to purge the water lines with air and then add some pink stuff to the couple of P-traps I have. I can do all of this in 5-10 minutes and keep on truckin... We camp in ours all winter long around here in the high country of Virginia...
This of course becomes more difficult having the large homes on wheels...
Roy Ken