Didn't Florida get freezing temps last year? Depends on the coach, which you haven't identified. My coach has basement heaters to prevent any problems in the lower half, heaters and a furnace to protect the upper half, and double paned windows to keep the cold out. Give us some info on your coach and you'll get better answers. That said, a simple light bulb, 60-100 watt left in your sewer compartment will generate enough heat to keep your pipes toasty. If it's freezing temps at night bring in your water hose and use the water pump. Only bring out the sewer hose when you're needing to dump. Daytime temps everything is back to normal....
Remember, a happy wife makes for a happy life....:W.....Dennis