I modified my BT5245 with a simple change. The power lead to the backup camera going to the original radio was powered by a tap to the rear passenger side backup light. So when putting the transmission in reverse, the backup lights came on, and the rear camera was powered up.
I moved the tap from the passenger side backup light to the passenger side parking light. I turn on my parking lights whenever I want to see whats going on behind me. This saved opening up the dash, installing a switch some where, and running wires down the frame to the backup camera.
Note with this approach you no longer have automatic camera activation when you put your gear into reverse.