I'm assuming you're still asking about highway techniques. If you've read that many threads/articles, then you probably already know the basic prescription for freeway driving:
1) Slow down. (Have you figured out at what constant speed your truck gets its max MPG?)
2) Drive with load (DWL) where possible - you really need instrumentation to do this, either a vacuum gauge or onboard MPG display. See the description of this technique in the
hypermiling tips list.
3) Aero mods. Have you seen
bondo's aerodynamic F-150 truck cap? He claims an improvement from 18 to 22 mpg on the higway.
There are quite a few mid-size and more than a couple of full-size pickup owners on the site. Hopefully others will chime in with tips/encouragement.