Alternatives to traditional exhaust-based cabin heat?

The concept of directing outside air around a hot exhaust and ducting it into the cabin has always seemed like a terrible idea to me. It seems fraught with potential for bad odors, carbon monoxide poisoning, fire, you name it. But what's the alternative? With a liquid cooled engine you can tap some of that hot coolant with a little automotive-style heater core and fan. Some pusher canards have rigged small ceramic element 12v heaters with fan. I have even heard of some folks using electrically-heated seats, though the ready-made automotive solutions I have seat draw up to 5 or 6 amps per seat.

Yes, I know that the hardcore KISS solution would be to forgo the heat altogether and just dress more warmly, but I am looking for something a little less hardcore. For example, these little 10cm x 15cm (4" x 6") heating pads (out of stock at Sparkfun.com at the moment but still available elsewhere) draw just 600mA each, so six (one under each thigh, one in seat back, X two seats) would draw just 3.6 amps altogether, just 1.8 amps when flying solo. A circuit breaker, some wire, a little 12v to 5v converter, the heating pads, a potentiometer/switch for each seat and a couple of indicator LEDS seems cheap, simple and light. Might this be a way to provide some crew comfort without the traditional exhaust-based system? The first half of this video talks about these pads...voltage control is important!