I have also installed a dashcam using a similar installation although I only put in a front camera and not the rear. In restropect, I probably should have also put in a rear one.
Several things I noted in my installation:
- The power cable for the windshield mounted camera should probably not be run up the same side of the windshield that contains the radio antenna (the RH side for US cars). Radio reception is already problematic enough with the radio antenna going up inside of the windshield. Putting a 12 volt wire next to the radio antenna will only make radio reception worse. Put the wire under the plastic molding on the LH side of the windshield. If you do this, the wire can be hidden behind a rubber molding strip of the same type used on the RH side for the radio antenna. It is TESLA Part No. 6005503, and the cost is approximately $30 (pretty expensive for a strip of rubber but it makes both sides of the inside windshield identical).
- A dashcam that is on all the time will run down the 12 volt battery. To forestall that possibility, I installed the Blackvue Power Magic Pro which will shut off power to the dash cam if the battery voltage level drops to a certain level.
Hope this is helpful.