[Big Dave]

I've been off this board for too long.

I had a 23 degree aerocap and while it may not have been optimum, it was damn effective. +3MPG over and open bed. Completely impractical: Limited bed storage and I couldn't see jack through it. But I gave it 3 years' try and it did work.

I replaced it with a hard tonneau. Not as effective for MPG +1-1.5 MPG over an open bed. But I had good visibility and easy access to the bed. Bad news: A strong wind got under it and I wound up chasing it through a muddy cornfield. C-clamps are not enough. Bolt it down to your bed or you will eventuall have to chase it.

What I'm thinking now is a hybrid. Put a ril wedge under the tonneau to raise it up to about a third the way up the rear window. No magic angle, just the height that doesn't impede my rear view. Obviously some sort of closure on the front to keep rain out. (I like dry cargo) this ought to give you about a 8 degree slope.

Follow up with something like Bondo's Drag Shield. That should give you aerodynamic performance closely approximating a optimized aeroshell but retain visibility.

I now have an ace body man to go to, so I'm not a bit squeamish about drilling or welding to my bodywork. Keep in mind, automobiles are built with mechanical fasteners and welding for a reason. Never underestimate the power of the wind to rip up sheet goods.

BTW, my air dam is entering its tenth year of service and shows no damage. It still looks weird and still works like a champ. The material - 3/8" ripstop conveyor belt is expensive, a real bearcat to fabricate, and nearly indestructible.

My next frontier: Mooneyes and rear fender skirts.