Great info John.
It's funny, I'm just down the road from you & I'm doing just about the same thing. I'm keeping a Pelonis Cube Ceramic Heater running, set real low, whenever it's getting down to freezing temps. So far everythings working fine & it's nice to step into a mildly cozy trailer in the morning instead of a cold one.
I've also considered setting up some temporary skirting around the Scamp
to keep the cold wind out from underneath. That alone can keep things from freezing for those overnight dips in temp.
Since I'm using my Scamp daily as my Computer & Ham Shack, I would think that just having the heater running in the evenings could keep things above freezing in the overnights here in at the Beach. Unless we have real nasty weather, most freezing temps only last for a couple hours early in the morning before daybreak. But I also think it's really good insurance to keep the little heater on low overnight just in case.
Happy "Warm" Holidays