My experience
I trimmed my skin per plans, as I can see it would be very easy to have a serious head strike if things go bad. I experimented with some 1/4" styrofoam glareshield "inserts" in various shapes that could be velcro'd in place with mixed results. I have a small GPS mounted top center panel that is most affected by reflections, and for it, I made a small hood of black stiff cardboard that helps a bit. The biggest reflection advantage simply comes from my shirt color believe it or not.A white shirt is bigtime glare, black shirt, no glare. For cross country flights, I have a Nexus 7 tablet on a kneeboard..easy to see. Under no circumstance, do I want any rigid glareshield in my -4. When I do a "panel upgrade"one day, I do plan to inset my whole panel about 4"-6", which will require some major structural mods, but that's where it really needs to be in my opinion.