I don't spend my winters in Florida like Ken, but I have never winterized either in over 4 years. But then I live in my Designer full time. I just keep the furnace going when it is below freezing and no freezing problems down as low as 8 degrees F several times last winter.
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