[Prematuregrey]

You'd be better off using a bed cover or removing the tailgate (mythbusters proven?). If you were to do a "skid" plate, I would think the size of it would be weight prohibitive and possibly cause heat issues due to air flow and the inability for under hood air to escape.

I would be interested in seeing your results, but skeptical of the advantages. I know when I panned my 4Runner from the bumper back, it had no gain in mileage. Although with the lift, long travel front end and tires sticking out, it's not really a platform to judge mpg adders.