i believe there is an anti syphon device.
as said, only way is to remove tank, use fuel pump, or remove fuel pump.
I had to do something similar with my old Mazda MX6. to get the fuel out, I used a syphon pipe, removed the fuel level thingy and did it that way.
curiously, the police drove up the street (we live in a cul de sac) and that NEVER happens, so I think the neighbours down the road spragged on me. the police didnt say anything, just drove off.
its very dangerous though, so personally id remove the tank and pour it into your containers..