Wow! Take a sabbatical from Ecomodder.com, and all sorts of new things appear.
It's nice to see yet another person using this FoamulaR stuff. I have an aerocap made out of this stuff too, but unlike yours, mine just bolts down to the existing tonneau cover rails. Good for my purposes, but probably not for what you want to do.
The Makings of a Pickup Aerocap: T Vago’s Dakota
My thoughts of side tapering are probably not "orthodox," as I have pretty much figured out they may not be as good as what would be expected. My theory about this idea is that the aerocap ought to become progressively more and more like a chord. This should serve to minimize any power-robbing vortices that would form on the rear of your truck. My version 2 cap currently nets me about 10% savings in fuel economy, but I think that I could push the savings up to around 13% or so by replacing the tapers with a more chord-like cap.
