a challenge. My first guess is some of your fuel maybe coming out of tank but not going out via the engine. As bad as 30 mpg sounds, you are 50% below that - when you are lucky!
I would pull your bodywork around the engine, just so you can do a visual (leaks and or bad hoses).
Then I'd pull a spark plug and see what it it looks like. The stock bike doesn't come with a good plug, but it gets the job done. At 20 mpg, I would wonder what it looks like. If you are really dumping that much fuel in the engine, I would imagine the plugs would show you are rich. Another way to check if you are running rich since the mpg is so bad, is wiping your finger in the exhaust tips (when it is cool; NOT when its running). If you are really dumping fuel inefficiently in the engine, everything downstream will have a lot of soot.
There is the theory that the excessive heat in the 2013 bikes, boil off the gas in the tank to some degree. Do you always have a heavy gas smell? If you have the side body panel, perhaps you could wrap just the exhaust pipe that runs parallel to the gas tank to help lower the temp of the gas tank.
are you mechanically handy?
Jerry