A few thoughts:
1) I'm with popimp: recording your fuel consumption has to be the
very first step.
2) next most important step: install efficiency instrumentation
of some kind to hone your driving technique.
3) I'd also consider a block heater or 120v interior space heater, so you can stop idling the Jeep to warm it up.
4) Look at the latest crop of GM SUV's: they all have
significant air dams below the front bumpers. You could make a removable one so you can still have your approach angle for playing in the mud.