Our Rockets have big motors with a need for big amounts of fuel to keep her moving and cool. I have a Dobeck Performance AFR Plus on my Rocket. I can change the AFR to any I choose. If I want extra lean I set it to 15.5. But really all that does is make my right leg hot and doesn't really save any fuel. So I don't do that anymore. I run ethanol free gas so I keep it set on 14.2. With ethanol I change it to 14.7. If fuel economy is most important, consider using a smaller displacement bike. Something that gets 50+ mpg like a Bonneville. Just a thought.
You know thinking about some of the touring I have done, yes it is nice to get 40+ mpg but the even if only getting 32 or so, touring on the Rocket is so fun that the mpg factor just isn't all that important. Think of the fun you are going to have. Man I wish I could take that tour with you.