That's why I'm only looking fer an inexpensive lightweight cap that's aimed towards the aerodynamic side. I know it's gonna take a few trials to find what's gonna be right fer the materials I have on hand...hence the topic of this thread.
I believe it's possible to make a simple, low-cost lightweight aero cap...just have to find the right design. I'm sure one could make the entire cap out of coroplast with coroplast beams as support and with some sort of windows fer visibility. I look at the postal containers and bicycle shields as inspiration...