An alternative is to blow out your water lines instead of winterizing with pink-stuff. Although I am a "pink stuff junkie", blowing would provide better protection than nothing at all. The miniscual droplets of water in the pipes won't hurt anything, but if it got much below 30 for any length of time at all, you'd be best protected with the "pink stuff".
About heat. If you're storing off site, you'll need to be hooked to shore power, as your battery will drain pretty quick running the furnace. Depending upon temperature (say 70 degrees inside when it's 30 outside), will probably drain your battery running the furnace within a day or two at the most.
If you cannot monitor it, accessable 24x7, immediately, I would recommend do not attempt to heat with anything.