yeah I should have put a / in there ---- "Off-Road or Lo-Range"...I wouldn't consider an overland route/fire roads/jeep two-track as low-range territory. Sure, there may be obstacles or short sections that require it but there's no reason to be in low-range full-time for such a track. I have been over loaded in both the GX and the 200 in Big Bend through very sandy and rocky sections for more than 100 miles and I never saw worse than 12mpg, YMMV. The GX did see 9mpg once but that was with three grown men, their gear, all while towing 3500lbs at highway speeds through mountainous terrain. I am fully aware of how range works and what should be considered and it's obviously relative to your particular vehicle, load, and where and how you're traveling. The example I was referring to was in regards to a 150 mile track that has fuel stops at both ends, this should be doable by any modern vehicle on it's factory tank and range with ease.
Anyway... just did 400+ miles on dirt roads in GA/NC/SC and 600 miles on Pavement - fuel economy was nothing close to what it is a daily driver..
Like I said its totally condition variant. So you need to plan for that. you also need to understand your trucks loaded fuel usage, then make a decision about what you need to do or not do in any case.