Here are the positions I finally settled on.
Though I had bought a 3M screen mount, and a suction screen mount I settled on two home made brackets I made out of some bits and bobs I had kicking about [ the same bits of "that could come in handy" bobs that my wife has an obsessive hatred of] Anybody else notice how perculiar the female variant is?
Though not used as intended the bought brackets were cannablised to afford the home made brackets adjustability on the horizontal plane. I cut the threads off the ball joints, and screwed [with a dab of super glue ]them into the camera "carriage" that comes supplied with the camera. And I also super glued the plastic thread housing to the carriage.
I settled on home made brackets because I felt they were more descreet. The front bracket was made from one of those blanking plates you find on PC Towers, to facilitate the adding of graphics cards and the like. The rear one needing to be longer in length , well I used a large-ish circlip I had lying about, fashiond to it's initial flat disposition with the aid of a two and a half pound lump hammer.
I must point out I got my insperation to fashion my own brackets from horaceJC's post 30 0n this thread, given we both have the same model of car, the Focus Mk2.5 with the rain sensor housing.
I found attempting to fit a bracket up behind the mirror, ment you caught a view of the rain sensor housing that looked like you had a massive spider trapped in the lense of the camera. I know the video would surfice as a record of an accident, but I suppose I'm a purist in that regard. Besides viewed from outside or inside of the car because the camera had to be sited away from the rain sensor the camera was by no ways "hidden"
I personally reckon it is more discreet where it is currently sited, plus the fact it is easly adjusted to catch any action happening to the immediate left or right of the passenger/ driver doors
And it can be removed from the car more easily without upsetting it's angulation than if it was tucked up behind the mirror.
Though in my case given where I live, and even though the car "sleeps" outside, I leave my dash cams in situ. I also leave the rear one running when parked in supermarket car parks. The later [based on personal observations] is because primarily the multi tasking female variant that frequents such places in large numbers usually has her mind on the next task instead of the one she is currently engaged on
I did have an initial problem with the rear bracket in that the test video's displayed vibration. You see unlike screen mounted brackets, that are mounted directly to the screen or attached to housings themselves attached to the screens. They don't pick up road vibrations transmited via the suspension up through the body shell. Because said vibrations are dissipated on the rubber seal that sits between the body shell and the windscreen.
My rear bracket being attached directly to the body shell [ and possibly being made from a circlip didn't help] Problem solved by just super glueding a cut down rubber "grommet" the likes of which protects cables where they enter into metal socket boxes. It in it's self sits up tight against the tailgate internal trim.
Both cams will be hardwired to the ignition , as you can see from the photo's I'm still awaiting delivery of the front cable, but will update when it is installed.
UPDATE:
As you can see by the updates photo's the 12v to 5v hardwire cable came today for the front cam, and now both cams are hardwired, job done.
Now the amount of cable from the 12v/5v converter to the mini USB connector is actually 16 cm in length. Not long enough for me to hide the converter in the headliner and connect to the Mobius where I have it sited. So I took the top trim off that conceals the wires for the rain sensor and auto dimming mirror. Filed a slot in the bottom of the trim where it meets the mirror ball socket to facilitate the cable exiting the trim to connect to the Mobius, meaning I could conceal the converter behind the cable trim.
Pleased with the overall result, a nice and neat instal hardly noticeable from inside and out. Now whilst the rear cam is not as inconspicuous from the outside as the front cam, I still reckon its better than having a mount, cam and cabling on the rear windscreen.
Having said that, the Scosche mount looks a tidy job if you don't mind shelling out £16. Though I cannablised a 99p suction bracket to make my rear cam bracket.