Mate, now that's why I asked - for some nice thinking. Good idea about that. Last thing I want is to hook the 12v (or 14.4v??) from the lights into what could be expecting 3-5v. Could be a very expensive exercise. The only accessory power I could think for power of are the two plugs that the smoker's pack plugs into. There's one just below the headunit, which I have powering the HVAC and headunit, and the illumination for the HVAC & h/u dimmer, and one behind the centre console bin. That one powers the new monitor and a wire running under the carpet and back seat to the camera. And now the illumination pin for the leds lighting up the HVAC buttons (must have missed those wires when I installed it - which explains the fumbling trying to turn on the demister at night ). Though I did just buy the boot power socket, so I think that's another - but that one may be permanent - I have no idea (it was permanent not accessory in the old's Prado).
So yeah, I can turn the headunit to rear view at any point in time. So you can see that tailgating car that the wing hides.
Might go for your style camera. Looked at that, but wasn't sure it would point in the right area and was wondering about it being off centre. Sounds like it works well and looks nice and neat. I think I can afford $20 to try considering you're happy with it.