It looks like the Blackvue battery pack I posted doesn't work with all cameras. It looks like the power output is only 2 wire so it can't tell the difference between constant 12v or switch 12v. Looking at Blackboxmycar, there's another battery that does support 3 wire output. Also, a new LG unit is out but no reviews on Dashcam Talk.
Yeh sorry bud I should've clicked your link I thought it was for the camera which I already read tons about. I'm sure with a little reading, research and fabrication this could be made possible. Lots of car alarms use gel pack battery back up systems. A couple of UPS batteries in the trunk with a little wiring could work too it's just the sensor part I've never had much luck with personally.