[Big Dave]

I keep a foot in both camps - ecomodders and pickup trucks. (BTW a good way to have two groups hate your guts. Ecomodders think I am trying to salvage a hopeless idea and the truck guys think I'm gay. Good thing I have a thick skin.)

One group of truck guys who really need something are the "drive-away" guys. These guys use dually pickups to deliver RVs. They never get backhaul so the return trip is just pure expense. Can't do much on the paying leg, but the return run offers a possibility.

Driveways have to have fifth wheel capability and a clear bed rail, although the bed rail could be a inch higher. When they are towing everything else has to be below the bed rail.

What I am thinking of is a quick-deployed bed fairing. Make it like a snap-on tonneau but sloped as much as possible. I'd have a hinged headache rack to provide front support. He puts up three or four unequal length wooden bows and pulls the tarp over it and snaps it on and drives home garnering better fuel mileage. Before he picks up another load, he folds his tarp up and lowers the headache rack, clearing the bed for towing action.

Using a tarp means the fairing has to be convex. Driveaways have eight foot beds and the cab top is roughly two feet above the bed rail. If I'm doing my arctangent right, that 2-in-8 slope is roughly 14 degees. Not optimal, but close.

But my prototype will be on my truck which is a short bed (80" long). I want to play with the angles. I'm thnking the front half of the bed will taper to 10 degrees (1-in-6 slope) then transition to a 12 degree (1-in 5) slope. this will reduce the height of the back of the tarp to 9 inches above the tail gate top rail. I won't get quite the wake area reduction I get now (one inch above tail gate top rail) but the gentler angles will keep flow from separating better (current average angle is 17 degrees) and maybe a tailgate "plug" can get me some more wake area reduction.