This is so silly.....need extra range? Buy a couple jerry cans, a stick or flux core welder and steel to fab a mount on the tailgate for them! If you don't go nuts w/ the welder, you'll still come in aboult $100 shy of the petroworks 15 gal price tag and about 5 gallons over the final capacity(and you will have a welder at the end of the day!).  Besides, all the folks who are complaining about getting 20-23mpg should hang out w/ some jeepers....in stock form my 4.0L buddies get 14-16 mpg and the 2.5L 4 bangers are jumpin for joy when they get 21mpg......... and thats pussy footin it!ÂÂ
No matter how amy times you gotta fill up, gas will cost too much. I'm hoping to find a 5 gallon fuel cell so I'll be a little lighter. Maybe less weight will equal better milage....or at least better hill climbs! Either way I can mount it high up and worry alot less about hittin my tank!