I've recently added a Zumo 550 to my R1100RT. I have it mounted underneath the accessory shelf so there's a small hint of something like shade, but I still can't really see the screen in sunlight.
I've seen guys with gps on their bikes and an added wrap-around (top and two sides) sun visor of a size big enough to do the trick.
What I haven't seen is where i could buy one similar.
thanx in advance