Walter,

The most important function of the glare shield overhang is to make sure that a forward segment of the windshield is shaded from reflections off the lighted instrument panel and your clothing at night.  This can be designed with a cardboard shield, a shiny material simulating the panel, a flashlight and a darkened work area with you sitting on simulated seat in the unfinished cockpit.  Better yet, go flying in a finished IV at night and use a tablet of paper under the glare shield to test multiple positions to see what you can see outside during the landing phase.

There are many sun angles that can defeat any glare shield.  You will probably get better panel shielding from the cabin structure.

For a rounded leading edge, I glued up a 1 inch by 1/2 inch thick piece of foam on the aft edge of the shield and wrapped it with 2 layers of glass.  You may want to make it thicker and consider adding wires and panel flood lights located on the forward side of the "bulge".

Scott Krueger
LNC2 - N92EX - We live in a bubble!