Polaroid might work if you do this:
These are clip on polaroid sunglasses from our favorite variety shopping store. With a dremmel tool the bottom part of the clip-ons are removed which means I can see all the LCD displays, plus the in cockpit vision from outside viewing is almost instant since the factor difference in light levels between outside and inside is about 10 to 1. For my canopy there are no stress areas that would make it appear like an oil film or dark areas. Also with the canopy curvature, the polarization angles are tilted slightly down on the lateral left and right which means if something is polarized to one eye, it is not to the other, so the object or glint is always visible.
Bill McLean
RV-4 slider
lower Alabama