Hey guys, I went and found some pics of the truck, so we can see what he's working with.
From the looks of things IMO you could help with an air dam (like you had in mind) and skirt the side of the truck from the end of the black step area all the way to the mudflaps. For the mirror on the passenger's side on the hood, maybe a parabolic "wind break" would help a bit.
Also, there seems to be a lot of ground clearance under the truck. How about an impact-safe skirt on the side that goes as low as possible/legal. Impact safe, meaning that you can high center without tearing it up, like some kind of rubber sheet or coroplast.