freezing weather

From my reading you are living in the coach while traveling. I assume you are connected to electricity. That means you will keep it warmer than usual and will run the water from time to time. Closing unnecessary slides will help in the cold. I also use windshield washer fluid to flush the toilet. It is rated for very cold and will keep black tank from freezing when mixed with water. Running the water every couple of hours should keep things from freezing in any low points. Don't open the bays unless absolutely needed. Placing a sensor in the wet bay for remote thermometer will give you peace of mind.