The three smoke pictures need more explanation to me. Is the one that puts the least amount of smoke in the wake of the camper the best? That would be with the wing in the middle. It also seems like they have less smoke input on that picture and I realize none of them are real pictures in a real wind tunnel but some kind of computer models. The problem with getting the wing back more toward the camper is on a pickup is what happens with the air between the cab and the wing unless you put a cab height topper/shell on first, then the wing on the topper. I'm thinking the topper/shell probably hurts day to day compared to just a bed cover. And is expensive and heavy.
This is the other picture from that Rv.net thread
https://www.tc.gc.ca/media/images/pr..._eng_fig11.jpg