Have realised I don’t have after pictures and they are a bit out of orde. Will add more.
It runs purely off the power to the rain sensor, no hard wire. But the rear cam wires to the front cam, so a cable still has to be run. It even has parking mode with this setup.
The camera comes in a new case/trim piece. I scratched the original slightly taking it off. The new piece is black, not exactly the same dark grey colour of the original.
In the picture with the broken (white) clip you can see the nylon “cable flex and draw tape” (aka fish tape) that I bought from b&q for £10 that I used to got behind the airbag at the a pillar and into the boot lid through the rubber cable boot.
I removed one other trim piece (on the boot lid) which was actually easy compared to the ones around the mirror. I watched a couple of videos where this was done, the best was the Deutsche Auto Parts video where they put a clubsport spoiler onto a normal gti as they don’t get the clubsport in the US.
The hardest thing was unplugging the power cable to the rain sensor or auto dimmer rear view mirror (not sure which it is). In the process I actually broke something, but eventually I found a way that if I had known from the beginning would have been super easy and non damaging - basically I used two mini flat head screw drivers from an Xmas cracker set from either side to grip and pull out. Their instruction video just had you pulling it and I broke the clip by trying to wedge it from underneath.
At the front it’s super invisible from all angles. And at the back it’s just the rear cam on the window with its cable disappearing into the rear trim.
No issues to the dab signal that I can tell so far. I ran the cable on the left (uk passenger) side.