Not sure I want to risk using my T-Stat with an inverter incase it fries... I don't trust inverters all that much but the temps in the car will be pretty much stable and we are only stopping for half and hour to eat. The human heat pad may be a really good option. I just want to keep the ambient around 75-85 so I can run some tests at least.

I can't seem to locate shipping heat packs. I am going to make a few calls today to try and locate some though.