I did some calculations and research on this. I forget the exact numbers, but a gas tank in the sunlight can get up around 5 psi internal pressure, which is about what the common portable gas cans are required to withstand. The dangerous explosive mixture isn't reached until a considerably higher pressure.
I bring my gas to the airport in the common red 5 gallon plastic container, and I have a rig using a foot pump (made to fill air mattresses) to pressurize the container. The can sits on the ground, and I can easily pump the gas several feet up to the tank in my Kolb. Sure beats holding the can over my head.
http://smg.photobucket.com/albums/v4...t=Dsc01919.jpg