[Pyrotechnic]

Well if it's a long bed, you can fit a Suburban tank. Something like 40 gallons.

Also, if you need extra fuel flow, don't use two tanks at once. Modify the sending units to have 1/2 inch pickup tubes, then run 1/2 inch fuel line or -8 AN line to the pump. Some manual valves would be best for this application, as no stock selector valve has that big of a fitting or can flow that much fuel.