[aerohead]

Sounds good.It will work.And if you'll start out gently(girly-man talk)with the angle as Kamm and everyone else recommends,the further back,the steeper it can be,as pressure is building and the airflow is decelerating.This is what I was trying to get across with my Cinderella and clockface analogy.If the back top of the cab is 12-o'clock high,the line of your canvas follows the sweep of the second hand.At five seconds after 12,your flow separates.If you scale the clock face up to that of the truck,such that your tires are sitting on the ground plane,which bisects the clock rim horizontally at the 5-second mark,and the top of the clock rim at 12-o'clock is at the back of the cab top,The line of the clock rim curving back and downward is what airflow will follow without separation.As long as you have attached flow up to that point,it will work for any vehicle.It's basically what Farman,Jaray,Klemperer,Kamm,and the rest discovered and it will work on those dead-heading trucks.Go for it,and good mpg to ya,Phil.