Bro,i may have a solution for you!
I have some specially made racks that take 2x 10l jerry cans.(1 can either side) these should bolt straight onto your bike, they sit nice and low (bash plate levelP so they dont affect the centre of gravity too much.
The question is doo you need so much fuel? are yoy crossing the Sahara? what does your route look like? Bear in mind extra fuel means extra weight, which on a trip of this nature is crucial!!
I have a mate that has GOS co-ords for ALL the fuel stops in africa,formal ands informal.This info is vital to route planning.
Youve got my details give me a buzz and you can check out those racks, i can then also hook you up with those details.
What i strongly recommend is that you join us when we go riding in the Atlantis due field, this will give you a very good idea of what the desert has install for you, and once you've been there you will see why all the fuss is made about weight. These big bikes are a handfull in sand even unladen.
Well the invitation stands give me a call, also we look forward to you joining us on some of the Cape XT Club trips.
All the best