I had the Zumo 550 but the buttons fell off. I bought the Zumo 665. I made a custom mount out of 4" aluminum bar stock. I mounted the plate just to the right of the left handlebar controls. i used longer screws and spacers so the plate would be above the control mounts. i routered out the inside of the control mounts so the wire could go inside of the handlebars.

i also wired mine to the headlamp. there were two wires with female connectors already there. GPS comes on with ignition. Also, it is inline with my handlebar controls and does not look out of place. Since I have 14" apes, the GPS is inline with my sight and the road.