The mounts are more important than the tank.
My G506 has two mounts that bolt to the frame rail and supports a 40 gallon tank.
One of the parts trucks I bought had nothing more than a tank held on with metal straps. I would say it was a 15 gallon tank.
40 gallons of fuel is roughly 350lbs and about $150 to fill.
Summit should have all sorts of fuel tanks.. just make sure you fab a solid mount.
