I wouldn't trust that first picture, since tailgate up is (empirically) better than tailgate down. And I don't see how the cab wing helps the half-tonneau. But there you go.
More to mull over:
The manager of the pizza parlor knew this gets better gas mileage (around town) but didn't know how much. It's basically a lockable trunk and spoiler combo. I think the ends could be beveled at 45° or rounded.