Many compressor dehumidifiers are protected against freeze up, either they shut off or they run a de icing cycle. If I stored the boat in a very cold climate (and had moisture problems when it was that cold) I'd go with the desiccant style. I don't know how much colder Petersburg is than Victoria, but I've stored a boat out of the water and outside in Sidney for five years with only a compressor dehumidifier running, no electric heater. Or course the boat is winterized.