I've had the Migsel mount on the clocks to mount above the speedo, but unless you have Tobinators it fouls the screen
I have found the best solution (for me) is to replace one of the 4 handlebar clamp bolts and re-fit with a RAM ball specific stud mount, which doubles as a handlebar clamp bolt
That gives you a RAM Ball mount and you don't have to attach one of those nasty clamps to the bars, which will mark the paint
I then use a RAM arm and a diamond RAM mount to the SatNav cradle of choice
Wiring.............I use a BMW plug on the end of the SatNav power lead and then plug it into the power socket on the beak
So when not in use, I disconnect it, so no potential power drain issues
If the bike is parked out overnight (touring) I pop the SatNav power lead socket, in a plastic freezer bag and stuff it behind the bars/beak
Simple solution and if I want to go without SatNav I just undo the RAM arm bolt and remove the lot in 10 secs
Best of all worlds