I only have a satnav for use in my car, however I have made a padded, 'slide in' cradle and mount out of aluminium to fit and use it on my KLT. It fits snugly on the top of the facia and is held in place by the screen.
My main problem is how to waterproof it. (I am not worried about lack of sound) The main point of water ingress will be the power point which is at the back and of course faces the direction of travel so will the 1st point to get wet should it rain.
I would be grateful for any workable ideas how to get around this.