Good comments on tune-up. Might want to get it professionally aligned in case there are camber or caster issues, aside from toe.
Wing+Cover could be interesting but I get the impression you'd spend as much time getting the right wing angle as you would simply building an aero shell. And with such low baseline MPG why chance it? Kach22i on here has a wing on his S10 but it's not tuned for efficiency. He claims better highway stability.
I would go for the proven stuff if it's only going to add a few MPG. That is, either a partial cover or an aerohead or BZP style aero cap.
"Basic redesign" assumes you are a company putting out a new generation of the truck and you will be changing the actual sheet metal of the vehicle. I suppose this would also apply to those who build custom beds, like (I believe) SkyKing and his Dodge Ram.
There has been talk about turning a step side pickup into an MPG champ because the narrow bed gives you a head start on plan taper. I've also yet to see someone build a custom aero bed with covered wheels and everything (narrowed axle maybe?) so perhaps I'll have to do that myself some day.
