[mcrews]

Not quite sure I follow.
Your finally rpm at cruise is a product of 1. gearing and 2. load.
we have discussed on here about increasing the diameter of the tire (not the wheel) to lower the rpm at cruise. I did this on my Infiniti Q45 and saw some nice results. I increased the tire diameter about 6%. The trick is you need to spend a lot of time at cruise to offset the little bit of mpg loss while driving around town.
2. load - the energy needed to keep your vehicle moving down the road at the same speed. Aero plays into this. Rolling resistance also (air up the tires to above 40psi.)

Point is, you cant arbitrarily set the rpm to what ever you want with your current set up.
I just remembered you have a 4x4. I would imagine the rear gears are high and not really designed for a lot of freeway driving.