I had a 1996 FZJ 80 with the factory 25 mid mounted tank and a 24 gallon that went where the spare went.  Spressomon (similar capacity in his 100 series) and I left Tonopah, NV fully topped off.  Two days later after spending some time and lots of miles in central Nevada; we returned to Tonopah, as it is the only fuel in that area, on fumes (we were both very nervous the last few miles with the low fuel light on).  
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I use this as an example as your Wagoneer and an LC are similar in weight and thirst for fuel.  I started carrying an extra 5 gallon can with me after that trip.   On my current truck, I installed a larger main tank (52 gallons).  I prefer the single tank over the dual.  I had a square body chevy with dual tanks back in the day and factory or aftermarket, I prefer a larger single tank, YMMV.  Having said that, I am contemplating adding an auxiliary tank in place of the spare eventually.  Not totally set on it, but as you can tell, I like having plenty of fuel on board.  Been on too many trips where plans have changed due to having to find fuel versus going where I wanted to go.
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Jack