A win-win-win solution to this problem
I killed three birds with one stone to solve this problem. I have my tilt-up canopy set up for actual jettison-in-flight capability as I wear a parachute much of the time and do not want wire-connected devices that could interfere with the jettison process mounted to the glare shield. I also hate that when you open the tilt- up in heavy rain, a large amount of water dumps right onto the center stack of avionics, with the primary recipient being my GTN 750. One note, because my radio stack was moved about 5” to the left for a more pilot-centric panel, I did have to come up with canopy jetisson linkage that moves the actual pull handle to the right several inches, but it also increases the mechanical advantage of the pull and also provides a more secure slot, like an old knife-blade electrical switch, to hold the jetisson linkages securely closed. You can see the layout in the photo below. The jettison release is tucked behind the upper left corner of the iPad mount, which can easily be pulled out of the way for full access.
My solution for the GPS mount was to use .020 alclad to bridge from the upper panel top brace to the flange that the forward canopy closes against for the maximum possible width(about 19”), allowing for hinge clearance. This results in a water-deflector that routes intruding water to the sides where it drops harmlessly to the floor, and it also provides a perfect ground-plane for my G3X touch gps amtenna mounted rigidly dead center below the glare shield, which has a cooresponding cutout directly over the antenna location. With the canopy closed, the glare shield rests directly upon this added sheet of .020. Another advantage is that the upper panel is greatly stiffened by the added sheet, so it can withstand a considerable pull from either pilot or passenged using the upper edge of the panel to assist with ingress and egress. It is a win-win-win solution.
The gps antenna for my GTN750 is, of course, mounted externally on the turttledeck. This is all a work in progress that I will photo-document later.- Otis