Welcome to HU!
tip: Have a good browse through the menu - you'll find a lot of stuff you wouldn't expect, if you only browse the HUBB.
Also of course check out the DVD series for loads of thoughts and ideas about which bike.
My first thought is that you can always carry a space 2 gallons of gas on a rack on the bike for when it's needed. Much of the time it won't be! Too may people get carried away with large fuel tanks when you can always carry spare the very odd time you need to. 2 gallons IS small, but then you should also get great mileage on that bike, so your range might not be so bad.
Another thought is that there are loads of dualsport bikes that can be lowered significantly, the F650GS single or even the twin are great examples of well done lowered bikes. Many women as short as 5 feet ride them just fine.
Best of luck, and do keep us posted on your travel plans here!
Seek, and ye shall find.
Inspiring, Informing and Connecting travellers since 1997!