The way i do it is this, bought a fuel pump for a car(cheapest you can find) with 3/8" connections on both sides, then i bought 30 feet of 3/8 fuel line hose(can be automotive grade), cut it in two pieces, a 20 foot piece from the boat to the pump and a 10 foot piece from the pump to your storage container. I also extended the wires from the pump to 10 feet long, so now you have your pump 20 feet away from the boat, the battery 10 feet away from pump and more from the boat and the container about 20 feet away from the battery(battery=sparks, you DON'T want that. Now, remove the sender, stick the hose in the tank, put the other end of the hose into your container and assuming you connected the pump to the hose on both sides, go by the battery and connect red to + and black to -. The way i get rid of old gas is i give to the guy who cuts my grass(he gives me no discount on the bill :bang ), or you can give it to your local gas station, they have a special tank for that purpose. Good luck and be careful.
P.S Make sure the fuel pump is for GAS, not diesel.