Of course the Grand Design owners manual says nothing about this but I have a couple questions regarding the Tank heater on our toy hauler.

First, can it be turned on with a partial tank of water in it. About 1/4 tank? We are in upstate NY with the temps in the thirties tonight leaving early in the morning
Second, does it just warm the tank or does it get hot?
Does it run on electric or propane.
Is it on a thermostat and shutoff when to a certain temp.

Like i said the manual shows nothing.