While I agree that some of the other choices suggested maybe stouter, I think your mount will be fine where it is. If it gets damaged it will probably
happen in the garage or setting a helmet on it when parked or something like that. I have a radar detector mounted on the right side plastic top cover
and I worried that it was going to fatigue and crack. However after 3 years (maybe longer) and over 30,000+ miles there is
no sign of it, and mine is
out in the breeze not nestled behind the windscreen. Mine is on a diamond shaped base and maybe yours should be too, time will tell, but a painted
black
(not glossy, use flat or hammered paint) SS fender washer on top wouldn't hurt your install any, after all you are going to be occasionally poking at the
screen with a gloved finger right?.
HOWEVER (
this is where fm does his thingie from his soapbox) In my opinion it is mounted too low for safety. Unless you have an upper percentile spot
in the range of top 10% of self discipline, you are going to someday have your head down and locked on that phone for some reason and miss something important
going on out in front of you. I'd move it higher when you can, where your peripheral vision can assist you in avoiding an accident. Until then I hope your in that top 10% I mentioned.