I used to mount my gopro on a headrest mount in the mk7.5 for track and autocross, but that won't work in the mk8 due to integrated headrests.
I just got an adhesive mount and a 6.5" extension and I'm hanging the camera and mount off the overhead light in the rear.
I also got a 13" mount and tried angling it forward, but the longer mount, in conjuction with the not so solid mounting of the light allowed for a lot of vibration.
It's the best I've come up with to this point.
If this doesn't work, maybe I'll try mounting the camera from the rear headrest with the arm extending forward from the center headrest?