I carry mine in the gas can in my garage.
Where did you find a 1 gallon tank? I've been looking for one.my last motorized bicycle i was trying to figure out how to carry extra gas and ended up buying a gallon gas tank for the bike, the new one i am gonna be building will have a 4 stoke titan on it and they only hold 1/4 of a gallon so i will be very interested to see what people come up with. the nice part is i am on an island that is only 28 miles long and 8 miles wide and i will not have to mix oil and gas so i can just pull in the gas station and fill it up so not really sure if i will need to hold more. i should find out soon enough
Just an odd thought I had awhile back for a different kind of fuel tank. An old portable size fire extinguisher bottle, slightly modified, slung beneath the cross bar. That way you can do away with the peanut tank on top. It might give a more board track racer look if that's what you want. That still puts some weight up high though...