Steve,
The auxiliary tanks feed through the fuel tank cap, so if there is an aux tank with properly fitting tank caps, then yes, they will work. I'd guess that since the fuel tank caps on the 2000, 3100 and 3500 watt Champion generators are all the same, this new model will also use the same basic cap (07100.00). That's a hunch, based on the owner's manual available from Champion on their website.
The Honda extended run system will not work with the Champion generators, not because of a problem with the generators or the aux system, but simply because the fuel tank caps on the aux system don't fit the Champion generator fuel tanks. Change them out and the system will work with Champion's generator systems.
This link is to one of the "generic" aux fuel systems that works with essentially all generator systems simply by changing the fuel caps.
http://www.ipiindustries.com/service...ded-run-tank-1