Sean,
If it is just for a short time period (the coach is used every two weeks) with temperatures above 10 degrees, I would not even drain the water system. I would just turn on the AquaHot, and set the interior thermostats at 50 degrees or so and forget it. The AquaHot will keep the coach warm enough to prevent freezing conditions if it has power available.
In the previous post I was referring to a coach that is stored in below freezing temperatures, not one that is used on a regular basis. If you are satisfied that there is no possibility of freeze damage to the interior plumbing, and leave the AQuaHot on, the only possibility of damage to the AquaHot is if the unit malfunctions and will not relight. If that happens there could be damage, so it should be checked often. This possibility lowers to some extent if the unit is also running on 120V A/C. However remember that if the coach is not plugged into shore power, the AquaHot uses 12V battery power and will not operate if the batteries are depleted.
Gerald