We've done the winterize, de-winterize, and re-winterize thing for late winter/early spring travel, as well. De-winterizing is easy, and you can find any local RV service center "down South" to blow out the pipes for the return trip north. We don't like taking unnecessary risks of frozen pipes, and find camping in a winterized trailer somewhat inconvenient, but certainly manageable.
Not to be contrary, but we *never* travel with our propane on. For the fridge, in hot weather, we use those frozen blue gel cold packs and tuck them in the fridge when driving; then re-freeze them at night. The fridge is really well insulated, so this system serves us well. In cold weather, we've never had food freeze in the fridge due to outside temperatures (vs. too cold a setting in the fridge thermostat.)
There is some risk of fire/explosion with driving with the propane on, should you get into an accident. Nobody plans to have an accident, but they can happen so fast and in ways you cannot control. Once in Montana we nearly hit a moose running across the highway. Bambi the First got smacked by a falling utility pole (broken off when a car ahead of us hit it) that landed inches away from the propane tanks.
Our worries about winter travel have more to do with road and weather conditions, including road salt.