[special-K]

Extended cruise range. These trucks were used for everything trucks are used for today. These trucks hauled campers all over the nation, towed boats, race cars, travel trailers, etc. Hauling loaded into the wind in some trucks can cut your range down near 100 miles. I've been in areas where a ranch is 50 miles from a gas station. Half a tank drive home with little more than enough to go back for more. It was pure practicality and the reason that ever since we have had a dual tank option, then much larger tanks offered on pickups.

I've often considered just running the saddle tanks. I dealt with a tank on each side in 73-87 trucks for years. Not that bad. There's always the option of only filling the one side, if doing both sides is inconvenient. You would have the 30 gallon capacity, room behind seat, still have a place for the spare tire, and 100% bed capacity.
I like the screw-on doors for the period accessory look. But if they bother you, gas filler doors could be grafted-in for a finished look.