We are starting to look for an RV, either a nice 5th wheel, or Class A MH. A dealer recently made a point when showing the OPEN ROAD rigs, that these were "4 Seasons" in that the water storage tank, grey water tank, and black water tanks are enclosed, insulated, and have heaters.
As the old saying goes" been there done that;" we arrived at a Oklahoma campground just as the blizzard cold front that followed us from Colorado also arrived. The cold snap lasted two weeks. Our tanks filled up as our drain hose froze solid, and then the tanks froze. Another phrase we used was "don't make waves" as the blackwater tank was full to the flush valve. We had to use the campground toilet facilities, and eventually haul water for drinking and cooking. Fortunately, we had ample food and propane to last the duration.
We had been told to leave the B&G water drain valves open so they could drain. That might have worked with short drain hoses; the slow trickle of our useage allowed the hoses to freeze the thin streams of water. If the tanks and valves were insluated, and heated, we could have probably needed to dump once a day, sending a flood of warm fluid to the sewer, that would drain completely.
We plan to become full timers, so will be looking for an all-seasons rig.