It may or may not work as some have already stated, but I would not totally depend on it. I have an Edenpure in my camper that is set on 50 deg, even though I blow the lines and add the pink stuff to drains and toilet. The only reason the heater is in there is because there are times while working in the yard that I will go in and take a break, kick the heater up to 65 or so and have a beer or three. My yard is about 5 acres so it takes at least that many.
I strongly suggest to the OP that you go ahead and winterize.
Best Wishes
