First: I had to laugh at the thread title.
(Hint: made me think "high c.o.g.")
Second: do you have fuel consumption instrumentation?
Driving technique will gain you more than anything: basics like stop idling, reduce your cruising speed, minimize your use of the brake pedal. Those 3 will show you immediate gains at the pump.
Also keep in mind that any gains you do see will be numerically small (in terms of "MPG"), but large in terms of actual volume/cost savings.
EG: if your changes save you 1.5 mpg, you may be tempted to say "that wasn't worth it". But when you're starting from 16 mpg, do the math. The savings from an increase of 1-2 MPG are significant.
And people here will ask: do you really have to use that vehicle? Several members have bought compact fixxer-uppers that literally pay for themselves through lower fuel bills while they save the truck for the times a truck is really needed (which for most people isn't really very often).
You can mod any vehicle - even your Laredo. (Have you taken the roof rack off yet?) I'm sure you'll get some other suggestions.
PS _ Welcome to the forum.