Lonnie - you won't
eliminate water from your tank - aside from the condensation you may be picking up from the service station tanks, your vented tank always has ambient humidity [in FLA?] and if the tank is not absolutely full, there will always be condensation happening in there, most of the reason many old tanks are so corroded inside .... best way to maintain gas quality is to use the gas, don't store it -
drive the truck 
Bill