Here's how I do it.
I put the bike on the main stand and turn the handlebars all the way to the right. I fill fairly quickly for the first gallon and a half, but then slow down. I hold the rubber boot of the fill nozzle away from the filler neck, so I can see when the filler neck is starting to fill up. When I have it filled to within a few inches of the top of the neck, I stop filling and rock the bike very slowly back then forward. This usually burps out a pretty significant bubble of air that gets trapped at the top of the tank proper, thereby lowering the level in the filler neck and allowing me to put in a bit more gas. I then fill it up very, very slowly to within an inch of the top of the filler neck.
