Good thinking ! I've always been wary of losing those. In fact, I put some thread lock on every windshield related screw, as after my last 2000km trip i lost 3 screws. One side one that supports the GPS bracket and lower cymarc part ; one too shield attachment to black part ; and one that locks shield + assembly (black part) to the front end of the bike.I drilled the end of the thumbscrew and tapped it. With the help of blue Loctite, I used a stainless screw and washer to keep the thumbscrew from backing all the way out. I only have 610 miles on the bike so far but the screws are holding fine. I'll put them to the test pretty soon when I head for Alaska. With Loctite, I'm not really concerned about them loosening. Maybe this is a better photo:
Needless to say I used the blue thread lock, don't want to go overkill on those screws.
I love your solution for that part, I need to look into that.