Heating Trailer While Driving

I've had the water lines freeze up in the old Jayco. The big problem was that somebody turned on a faucet, and didn't turn it off thinking the water pump was off. It wasn't When we finally dropped back in the valley the trailer thawed, it pumped the contents fresh water tank into the sink, which did NOT drain because it was still frozen, so it flooded the trailer. Luckily it had a pretty small tank which was only about 1/4th full. Since that incident, the heat stays on. The couple extra dollars it costs to do that (if even that much) is well worth preventing freeze and water damage. But its your trailer, so good luck.