Yet another update:
Between downpours, I had the chance today to finish this long winded rear camera extension fit to to my dash cam. Well almost.
It seems that removing the upper rear brake light intact is rather difficult if not impossible. I carefully studied photos of this light fitting and watched a video clip posted on another thread, yet despite all of this I still managed to break off the über fragile red plastic brake light cover. As soon as the trim tool was lightly inserted to depress the spring clips, crack! I have read that this is a fit once only item that will self destruct if attempts are made to remove it. If this is true then what a bl@@dy stupid design! I actually think it's probably more a case of something being made down to a cost. Still I would like to know if anyone has managed to remove one intact and if so how?
I thought that this light fitting had to be removed due to the rigidity of the rear camera cable. I couldn't have any sharp kinks for the following reason:
The Nextbase rear camera is designed like a magnetic eye ball that attaches to a cupped bracket which is itself stuck to the rear screen. The cable exits the rear of the camera and acts upon it a bit like a stiff tail wagging a dog. Being rather inflexible, the angle of the cable dictates where the camera points so it must be very carefully fixed in place to ensure the eyeball sees the correct rear view. IMO it's not a good design and whilst it works well now that it's fixed in place I wouldn't recommend this rear camera purely due to it's fixing method.
Having routed the cable from the main dash cam to the inside of the tailgate I needed to drill a hole to take the cable out from inside of the void between the inner and outer pressings to beneath the upper tailgate trim.
The brake light fitting was removed to ensure that I could route the cable, fix it down properly for the reason already mentioned but mainly to avoid drilling a nasty big hole in it. Actually, drilling the hole would probably have missed the light fitting but I couldn't be sure of that before drilling.
I decided not drill the hole nearer to the rubber umbilical tube and then to run the cable under the trim due to complications caused by the said inflexible cable issue and the obstructions caused by the strengthening webbs on the underside of the the upper trim moulding.
Note: the camera is fitted in the middle of the rear screen. For some reason the rear blind bracket is mounted off centre.
Question:
I'm afraid I cannot remember which way round the rear window blind bracket was before I removed it. Not that it really matters but which way round should it be?
Tomorrow I must source a new upper brake light. They are £35 on Fleebay so they must be at least £400 from VW!
So, with the benefit of total ignorance and a smattering of incompetance this whole job has taken me, on and off, about a day. However, if I were to do it again tomorrow I could probably do the whole front and rear camera installation in about 2 hours and I definitely wouldn't remove that fragile brake light.
Thanks to all for all the help and advice.