In my opinion the navigator should be placed above the instruments behind the windscreen. That's a more DAKARISH STYLE....

Actually I'm in process of developing a GPS Holder that fits both the Garmin Zumo 660 and Garmin Montana! It will be an adjustable holder, made of cnc milled solid aluminium. Light, but with stability and design in mind. It clamps around the whatever 12mm bar you are using, for example the bar in the front. Anodized in black, red, silver or blue (i think...)

Another good thing about it, is that part of it will also fit the BMW F800GS and KTM 990 Adventure. Meaning you would only need to complement with the corresponded parts needed to fit the bike. IF you for some reason would change bike in future!