Hello , and
when my RV spent winters in Canada, I figured Oct 15th at the latest, drain all the tanks, by-pass H/W heater& drain, drain or blow out all the lines, hook up a pick-up tube, directly to the 12 pump and run RV-A/F through the system.Blow back through the supply tube to the fresh tank, and don't forget the city water hook up.
Draining/or blowing out the lines in the RV keeps the A/F stronger for better freeze up prevention.