We do not recommend mounting a Rotopax on the inside of our asymmetrical pannier racks.
It might fit when the wedges are mounted all the way in the back, but it is possible that, if the rear suspension is fully compressed, the fuel canister may come in contact with the chain guard.
For liability reasons, we don't list it as compatible.
In case you want to use your pannier set with a 1 Gallon Rotopax, please order an asymmetrical rack from Outback Motortek directly including the X-frame.
Another possibility, in case you like the idea of having an asymmetrical rack, might be that you use fuel bottles. We prefer MSR Storage Bottles to Rotopax for carrying extra fuel, because they are more configurable.