Okay, hear me out. You'll need a bucket or tank of RV antifreeze, a sous vide immersion heater, a small fountain submersible pump, and a hose. Get the fluid up to temperature—something hot enough to do the job but not so hot as to damage anything.
I drive a Chevy Volt PHEV. It has a 14 kWh (usable) battery. I put in a quick connection to the battery that I can hook an inverter to. The inverter can run the Reiff heaters on my engine and a battery charger without breaking a sweat. It might be able to handle the sous vide heater at the same time, but if you leave the house with the antifreeze already heated up, you might not need to heat it much.
How much antifreeze does it take to clean up a typical four-seater?
What about using the inverter to run some electric blankets?