Potentially a compound radius deflector on the transition between the cab doors and the leading edge of the sleeper? To help maintain laminar air attachment?
The transition between the fender and the top of the tanks / top step area is a definate concern..I think reflowing the fender such that it is more similar to the aero bullet truck design might be required.. (Effectively flattening the top by 2-3", and tear dropping it backwards onto the step in a more shallow curve)
Another thing I am contemplating is the effectiveness of putting a V chin spoiler under the front of the truck...from the centreline of the bumper underside..to just infront of the wheels..to reduce airflow under the truck..Obviously most things would not work in this area due to getting hit / damaged, however how would a 6" high BRUSH work in this area? like the below product
https://www.industrialbrushware.com....s.php?catid=46
worthwhile? or unicorn corral ?