There is also the option of cranking the engine on the starter, ignition off, if that configuration is available. Yes, I know this means you have to get in and out of the aircraft, but your choice. The engine will still gurgle with the filler cap on, but you won't hear it over the noise of the starter motor. Personally, I just pull the prop through, without offering my head up as a sacrifice. It's a Pioneer, so the height is a bit low for comfort.