That pic says it all, Dave. Auxiliary gas tank on rear rack, negating the poor mileage range, if using only the OEM tank.
However -like I've mentioned previously - it would be SOOOO easy to cover the aux. tank with an extension of the rear bag, or just any suitable bag , with a modified flap top allow fuel filling. And of course this means that you would already have equipped the aux tank to dump directly into the main - again, not a big alteration.
Bottom line - keep refueling as simple as possible.
If I were re-designing my touring setup, this is the way I would have gone. I spent countless hours fabbing up an aux. tank that replaces the rear seat. It works well, but only gives me an extra 100 kilometers of run time.
The TOUR TANKS are available in many configurations and capacities, all at incredibly low prices!
Cheers!