This may have been mentioned, but why not use smoke and mirrors?
For instance the Mobius can run off a battery and you can turn off the LED lights. Charge the Mobius, unplug the USB from the back yourself and let it dangle down, or unplug from the cigarette lighter so it is seemingly off. Set it to record at a lower crappy rate (bad video is better than no video) and it should last...an hour? (I've never used it off battery so I don't know.) With smaller recording clip sizes more will be saved to the SD card.