Someone once told me they never fill their bike up while sitting on it because if there's a fire (and fires at the pump are more common than you think) you can't get away quickly. That's not why I fill it on the side stand, but, it's something to think about; they've got a point!
I fill it on the sidestand, fill it up to the filler neck. If you're having issue with fuel driblling on the tank, there's a couple steps to avoid that. First, do NOT let the nozzle dip BELOW the fuel level. Make sure it doesn't get submerged. Second, hold the nozzle up in the filler for a second or two after you finish filling, tap it gently on the filler neck, then put it away. That's what I always do. Although in the end, a little gas won't hurt anything. The clearcoat on the paint is resistant to fuel (assuming a factory paint job, you'll have to check with who painted it if it's custom!)
If you do get more fuel sitting on the bike how much more is it? Seems like some people overthink this. You get what, an extra 1/8th of a gallon? An extra 5 miles? If that even? Seems easier just to hop off and fill it. I usually like to take that time to stand up anyway. I have long legs so I like to stand and stretch 'em!