Thanks for the write up JV3, lots of good lessons learned.
On the topic of siphoning gas from vehicles. With new vehicles, I think you will have a very difficult time siphoning gas through a line or filler tube. Like you had mentioned, most filler tubes have a check valve built into the line. Taping off the fuel filter underneath would not work either, because the gas would need to be run through the fuel pump to get up to that point. You may be able to disconnect the filler neck right at the fuel tank, and snake a hose up in there. But with vehicles being being built smaller and smaller, space for your hands is becoming a premium, and most often requires special tools to reach.
When I was a Auto Tech, we had a little trick to empty gas tanks before replacing fuel pumps. Sometimes the fuel pump was not completely dead, it just didnt have enough fuel pressure to supply the engine. So we hooked up a fuel pressure tester to the port on the fuel rail, jumpered the correct pins for the fuel pump relay, and held the bypass button on the pressure tester, and fuel flowed out of the tube, and into a fuel can.
You dont even need to have an actual fuel pressure tester to get this trick to work. There is a test port on most vehicles, alot of them are right on the fuel rail. Most will have a shrader valve inside(same as a tire stem valve). Just remove this valve(Caution: There still may be fuel pressure, so wear eye protection), and connect a hose over the valve. Then find the fuel pump relay and jumper pins 30 and 87(The pin locations are marked on the underside of the relay. Here are a couple pics I found that show what I am talking about.
You are going to want to use a good sized wire. A paper clip will just heat up and it wont work, too much amperage for that small of a wire. So, just jumper the pins, and the fuel will flow right out of the tube and into your container. Remove the wire to stop the flow. Its not a fast method, but it works. Wouldnt be a bad idea to research your own vehicle and see if it can be done.
I drive a 95 GMC Yukon, and there is no fuel tester port, so I would need to crawl under the vehicles frame rail, and disconnect the line off the fuel filter. This method will work just the same as mentioned above, you are just tapping off a line closer to the tank.