You can still get more than a dribble of gas spilling out when you undo that fuel line bolt on the tank, so be sure to have a rag handy to catch any spill.
Otherwise, it's safe to just leave the tank unplugged like TMiller said. Just don't tip it too far forward or sideways when there's still a lot of gas in there. Unlike the fuel line connection, the filler cap does not have a sufficient seal to keep gas inside for long.