youd probably be better off with a mk6 boot release retrofit. if it works!
Yeah, some of the vwnavi people have gotten a mk6 camera working on a mk5 IIRC. Will look for the thread tomorrow, it's full of europeans speaking english poorly so is a bit difficult to comprehend

And the Merc S and CL classes are offered with the FLIR as an option, as are the BMW 5, 6, and 7- series. Works quite well but the image is on the central screen. I think FLIR projected onto the RNS-510 on the console could be distracting!