I don't even try. I keep my fresh water tank full and disconnect the incoming hose when the forecast is for freezing weather and just operate off of the on board tank. When I disconnect the hose I disconnect both ends and leave it laying there. I elevate one end so it will drain and I can hook it back up to refill the tank easily. I've been doing this for 3 years full time and it works for me.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof