In the video below is a gate spoiler and cab attachment similar to some of my sketches and ponderings of the past.
Sep 8, 2017
Yoshi Suzuka
Pickup truck aerodynamics Drag reduction Part 2
Dang, he even used a sidestep/sportstep.
My sketches did have it going more to a half-round.
EDIT
I love the use of an extra long string over the top of the truck at around the 4:00 mark.