There are a variety of good radar detector mounts out there. My V-1 spent the first year attached to the brake reservoir with heavy-duty velcro, which worked great. (The power cord acts as a leash in case it comes undone, but I never had any problems with it, even on seriously bumpy roads). A few months ago I switched to a RAM mount setup with a security/weather case and security mounting bolts, and I now feel comfortable leaving it on the bike while I'm inside a restaurant eating dinner. (I do remove it over night, though).
The angle of the wind screen does not lend itself to the secure attachment of a radar detector suction mount. Some people have shelves that mount inside the windscreen that have plenty of room for a radar detector, GPS, satellite radio, etc.
If you're going fast enough to need a radar detector, you won't be able to hear it without earphones or helmet speakers.