[Christ]

So you can't see through plexi when it's at the right angle for a Kamm... same with lexan.

I wonder:

What if you made the kamm with 3" steps in it? Obviously, it would lessen the effect, but would it be that bad? I mean, you'd keep most of your rear visibility, still have an optimal overall angle (with more turbulence at the boundary layer, if the flow could even stay attached).

Does it work?

The view would look something like looking through the rear view of a car with window louvers on it.