Simon - Our bikes do 400km to a tank and we haven't had fuel problems (aside from some longer pistes we chose to go off and ride). Well, no, that's a lie, we had fuel troubles in Gabon due to our lack of planning and three towns in a row having either very little or no petrol. It shouldn't be an issue though.
Darius - No idea about the far north crossing into Cameroon or getting a visa at the border. When we rode Ekok - Mamfe it was dry and the road was fine. Cruising at 60-70kmh most of the time. But there were some big flogged out mudholes that looked like they would be deep, muddy and slippery in the wet.
Vladivostok - Denmark 2008... Finished.
Denmark - South Africa 2010-2011... Finished.