powersurge wrote:I understand that inverters are no way efficient.
Supersleeper wrote: There's power loss going from DC to AC. I'd rather have 12v DC heater.
True, but not really a problem, provided the inverter is inside the cabin. The power loss generates heat. Isn't that what we want? Obviously the downside is you can't point the heat coming off of an inverter. But maybe you could place it on your lap or put it under your legs or something. Or get a little 12V fan and run a duct around the inverter and point it where you wish. You get the same amount of heat per watt no matter how you get it. The only difference is that if you can heat your body directly instead of the cabin air you'll feel a lot warmer with less heat.
For similar reasons I've often thought of changing my home's CFL's and LED's to incandescent lamps during the winter. That way the light bulbs would have two uses, light and heat.