I did a quick search on the internet and found this
The CRF consumes gas at about 3.0 L/100km (that's 93 m.p.g., ladies and gents!) giving a range of 225 kilometres before manually switching the old-style fuel tap to "reserve," leaving 70 or so kilometres to find a gas station
Thats looks pretty close to 300kms to a tank, I have done lots of riding around BC and would think with a minimum of planing you should be able to find a gas station before you have to think about walking. Unless your riding with a bunch of KLR650s, but they would leave you behind with their crusing abilities. Getting a 300km range right out of the box I would think it unlikely that any of the aftermark tank manufactures would make a tank.
Maybe I am missing something?
TT