To answer questions, not happy with the Tesla solution and inability to easily access the video. I had a twin BlackVue system in my BMW M3, and it was extremely useful and easy to view the clips on the BlackVue app and all the clips joined together seamlessly.
Anyway, today I fitted the BlackVue cameras. I fitted a Cellink Neo battery in the rear centre console connected to the cigar socket. The front one was easy enough running the cable down the front pillar and under the bottom door trim and then under the front seat. I had to take off the rear passenger vent and drill a small hole in the rear console to feed the cable through.
The rear camera was a bit messy as it is stuck in the middle of the glass screen, so visible on the inside but not the outside; I had to be careful with the side air-bags when routing the cable to the camera.
If anyone is interested, I'll post some photos. I finished as it was getting dark but will test it within a day or so.
One problem I've notices is the front screen wiper doesn't clean the screen in front of the camera, so I'll have to clean that by hand.
Would be interested in photos to see where you have put them and how you've managed to route the cables please!