I know the thread's old but I have a Blackvue (one of the latest ones, cigar shaped thing) running in the front and back. It plugs into a Celllink battery under the driver's seat, which in turn is hardwired into one of the ACC spots on the fuse box. I turn the speed off on the camera telematics so you can't tell, haha.
It's a bit of a bugger to fit (a rear mount will need you to pull out bits of the headliner etc as needed) but not impossible, I never wrench on the car myself and I could do it.
Very useful bit of kit, stays on for a day or two after the car is switched off and records any activity around the car. Came in especially useful when I discovered my neighbour was dumping rubbish around my spot in my communal garage - identified him and had a stern word!