Not sure there is that many as you say I've had this before sw motech worked o.k https://bykebitz.co.uk/sw-motech-bmw-f800gs-quick-lock-gps-mount.html I just have the std Ram mount U bracket/ball mount affair now etc again works fine. Blocks the rev counter a bit but so be it.
This type is okay. The big bolts replace the handlebar clamp bolts. The heads are threaded to fasten the mount onto.
BMW part number 7680517 although I suspect mine is from a different bike originally as it looks like it's been squeezed slightly to make the bolts line up but that's not to say they don't make one for the f800.
Hopefully got one on the way, in 2 halves, I have the mount above coming but have had to source the black block thing separately, should all fit together.
Just need an older Nav to go on it.
Will put a wanted ad up.
Thanks all