Interesting. I've not heard of North American bikes having severe fuelling problems.
My Mk2 with an oversize windshield gets a litre worse fuel consumption than the Mk1 with a smaller windshield per fill up. Given the mule-like role to which you subject your bike I'm not surprised at your poor fuel consumption. Couple of straight roads between the PNW and Phoenix too.
A V1K would make a great pack horse. Almost the same mpg as the 650, more space, 21 l tank, would feel the load much less, and very little higher than the 650. But even more pavement oriented.
Frankly, it was all I could do not to call the SPCV on you when I saw your bike last year