Fresh water tank under camper-Camping in colder weather.

Our previous Class C had exposed black/gray tanks and low-point drain valves and the freshwater compartment wasn't heated, so when it was sub-freezing, we simply used a jug of water for teeth-brushing and coffee-making; and flushed the toilet using antifreeze. (Showers were taken using the campground's facilities) Anything that went down the kitchen drain got followed by a splash of antifreeze. Works sufficiently well until you get to warmer temps and better than worrying about cracked pipes/fittings.