I had an idea that I don't know if it did cross some ones mind before ,but i posting for it any way
![Smile :)](./images/smilies/icon_e_smile.gif)
I brought a phone touch screen protection (iPhone 6/Samsung note 3) and tried to measure it with my gps device (Garmin/Montana 650) and found it almost fit! With some trimming by a knife or a razor blade it was just fantastic!
I think it the way to prevent screen scratches ... I hope my suggestion is useful!
Enjoy the sand ,and play it safe
![Dancing :dance2:](./images/smilies/dance2.gif)
Best regards ,