I've been riding with a Lazer/Rader Detector now for some time with great success. I had it mounted to a small wind shield extension of my fly screen, but due to mounting tape problems I had to remove the extension and it is now mounted with Velcro to the back of the fly screen, and thou pointed down and completly behind the screen it still works great!
A cop buddy brought his Radar Gun over and did some tests on the set up. He explained that the radar and lazer signals would "bownce" all over the bike and reach the detector no matter where it was located, or in what position.
This seems to eliminate the need for a special mount for these units, the fly screen being the perfect place for them since it is in line of sight and close enough to hear.