1. Siphoning requires that your destination be lower than your source, unless you have a continuous pump (But if you had that, then why not use it instead of the drain plug, and put the gas in there first?)
2. Gasoline + PVC plastic is a disaster in the makingyou can't leave it in there long. It'll start disolving the kiddie pool. You'll also have to dispose of the gas, I wouldn't even put it in a lawnmower after that. Might use it to light the fire pit, but half a tank is good for a LOT of fire pit lighting.
3. Even with the engine out of the car, running the fuel pump isn't hard. The easiest place to get the fuel from is where it connects to the J pipe after that. You can run the fuel pump by jumping from the battery to the FP relay on the passenger side fender. (Look for constant 12V FP mod write-ups for where.) Really, this is a better option.