I am trying to decide on my extra fuel options for my Alaska run. Not because I thin k that I will run out anywhere, but because I know the fuel on the Dalton Highway is expensive Regular was over $5.00 a gallon in 2013 . . . probably need a home loan today for a tank!). I have already ruled out the traditional front rack mounts, because I want that space for carrying other things in the bags I mounted there and because if I have roto packs on, that is it - no other options until I get back home and take them off.
There are also other options for carrying fuel - First you need to decide how much do you need to carry . . . then how and where. Small amounts can be carried in Fuel bottles which can be mounted virtually anywhere on the bike safely stowed away in carriers (which can hold other things when you don't need fuel).
Carry extra fuel or water on any flat-sided case with the DrySpec Bottle Mount Kit one of our most popular motorcycle accessories.
twistedthrottle.com
The DrySpec Motorcycle Tool Tube Kit from Twisted Throttle is used to carry our MSR 30-oz. Fuel Bottle and any other accessories that fit.
twistedthrottle.com
There are also bladders that can be strapped to the bike - Giant Loop and Desert Fox seem to be the most popular/reputable. They are available in various sizes and again go on and/or carry fuel only when you are at that last gast station before treading out into the great unknown.
Carry the extra gas you need in the Desert Fox Trail gas bag for motorcycles. It can be strapped on your bike in any position. Folds down for easy storage.
twistedthrottle.com
Armadillo Bag expedition-ready liquid power reservoir: flexible, collapsible, lightweight, expedition-ready utility bladders for the safe transport and storage of liquid hydrocarbon products and other powersports and automotive fluids, available in 1-, 2-, 3- and 5-gallon sizes.
www.giantloopmoto.com
If you have hard bags, something like this may also be an option:
Quickly mount the TAN01 Outback Jerry Can by GIVI on your Trekker Outback Case with ease by using this remarkably reliable E148 Removable Support by GIVI.
twistedthrottle.com
At least these are the options I have found so far . . . Still looking and open to new ideas!