[smoothrunner]

Thanks for all the replies and insight.

I made the fog light covers out of lexan. I traced the outline of the opening through the lexan, then cut it. I found the screws in the corner helped to seat the covers nicely. Other threads recommended heating the lexan if needed to contour to the vehicle. I was able to seat it without heating. I used clear caulking to seal the edges and left with a small hole to allow condensation to drip out.

This is a convertible. It seams to seat tightly to the front. The edges are not terribly tight though. I wouldn't believe that the fan could exert enough pressure to make the top more aerodynamic. I agree with the previous idea of adding extra straps or tightening the existing ones.