After additional testing I have some bad news and some good news: Bad news: Don't use this method as it somehow switches your backup camera on while the car is on...even while driving. Unplug the 12v to 5v USB adapter and the camera turns off and everything is back to normal. Good news: You can use this method to switch your backup camera on while the car is on...even while driving. So now Plan B is to tap into the overhead lighting cluster. Bought one of these 12v to dual 5v USB adapters. Borrowed this well documented method of tapping of power from the auto dimming mirror port. Checked the switched power and polarity Of the 3 black wires. The left is positive and the right is negative. Tinned, soldered and shrink wrapped the leads. Tested 5v successfully. Mounted with double sided tape and tucked and Velcroed together. Done!