What about using the small aluminum fuel canisters that hikers/backpackers use to store/carry their stove and lantern fuel in made by MSR. They are made out of aluminum and have an O ring sealed screw in cap. They also come in various sizes, some would be just right for a tail bag. Plus they ARE MADE FOR fuel. Not sure I'd trust PVC with glued on ends, but thats just me
I've seen them at Bass Pro and Cabelas but any hiking or camping store should have them.
http://www.basspro.com/webapp/wcs/stores/s...0004000_350-4-4
Small, yeah, but they would be safer and you can always carry more than one.