If the boat is on a trailer, and you can get to the fuel gaude sender, you can use a simply siphon to drain the gas. Block the bow high to force the fuel to the rear, remove the gas gauge sender, and stick a "shake-shake" siphon into the tank, as far astern as she will go. You may need to put a piece of 1/2" copper pipe on the end of the siphon hose, and you can stick it thru the garboard drain fitting. Stick a gas can + funnel under the garboard drain fitting and start the siphon. Monitor and change gas cans as necessary. No smoking!!