Northwood's Desert Fox seems to be the best insulated toy hauler. We winter camped with our Weekend Warrior, but could easily run through one 30# LPG tank each day keeping it comfortable inside. I spent considerable time wrapping pipes up with insulation and adding Styrofoam insulation to exterior boxes so pipes would not freeze. We did not use the camper when winterized, I would run the furnace at 40-50 degrees while we towed it to keep it from freezing up. When we returned home, I would drain any remaining water in the tanks and water heater, blow out the lines and fixtures and dump some RV antifreeze in the traps.