This one is aimed at a more limited market but one that may be more motivated.
Around Indiana one sees a lot of “driveaways.” These are heavy pickups delivering RVs. They are late-model dually one-ton pickups – mostly Dodge and Ford. Almost all are diesels. They hook up a big (up to 36 foot) towable RVs and haul them from Elkhart to as far as the Gulf Coast. They have fifth wheels installed in the bed and usually have auxiliary fuel tanks and tool boxes as well.
The driveaway business never has backhaul. They have to deadhead back to home. These big pickups get about 10 MPG
pulling these rolling barns and usually no better than 13 MPG
There is little improvement I could offer to them while hooked to a trailer shaped like a Wheaties box on steroids, but on the way back they could benefit from aerodynamically cleaning up the bed.
What I envision is something like a “headache rack” and side and tailgate rails and snaps to support a sloped soft tonneau over the bed while running unloaded. Basically, a folding version of my bed fairing.
Driveaway drivers are used to relying 100% on side mirrors, so the solid bed cover would be nothing unusual.
When towing fifth wheel trailers these trucks cannot have “headache racks” because of trailer clearance, but if the “headache rack were folded down while loaded it could be erected for the deadhead home.
I would have the “headache rack” folded down over the auxiliary fuel tank with the tonneau rolled up while loaded. When unloaded the driver driver erects the rack and fastens it in place with door bolts. He then pulls the tonneau out and snaps it onto the snaps on the side and tailgate racks. Viola! A slick shape for the trip home. Five minutes up and five minutes down. He gains 3 MPG
from having up on the drive home. For a 800 mile trip at $3.70/gal that represents about $43 per trip less fuel cost.