Just saw this thread and it made me think (admittedly not always a safe or frugal occurrence). What about right over the radio?
The automount sits up there nicely (I just discovered). It won't actually stick there as the surface isn't flat enough for the suction cup. But using the automount isn't really what I was thinking about though.
I placed a 660 on the automount and moved it around up there. It clears everything nicely. It would also be below line of sight for riding, still in a good viewing position but out of the weather and wind protected by the windshield.
Using Garmin's motorcycle mount cradle and this automount as a guide (or even a donor piece) fabbing something up to mount permanently in that location and building a nice fiberglass enclosure around it to blend in with the fairing shouldn't be that tough a job. Something to consider.....