what is the best way to really empty out the boat's internal tank ??

I have a 17.5 footer with a 75 etec

will siphonning do or should I disconnect the hose to the motor and use the primer bulb to pump (suck) out all the gas from the internal tank.

I use the engine so few hours per summer I am considering using a proverbial 5 imperial gallon tank instead of risking "sludge sucking" from the boat's internal tank !