single forklift?
most customers i know of have some sort of storage tank but they generally have several trucks to fuel up.
for a single truck application quite a few i've seen just keep a couple 5 gallon cans available and keep them full, they have to go to the gas station and fill them up.

all depends on how you want to obtain the fuel and store it if need be. If you are going to be going through alot of fuel it may pay to get a tank and keep it maintained with fuel conditioners etc.