Yada-yada -

I have DEFINITELY used OTHER fuel sources versus products labelled "Jet Boil" fuel (ie. the hockey puck-sized propane cannister).  I'm talking about their propane model.  You mention 80/20 combo, so I'm wondering if you are using liquid fuel of some sort?  If so, I've not seen that kind of Jet Boil.

IF you're talking propane, I've used somewhat larger cannisters that screw on just fine.  I can't recall the exact name of them but they were pretty generic, allowed more fuel volume, & were less expensive.  

If you can get the name of a couple sporting goods stores anywhere along your route in Canada before you enter the park, you should give them a call.  I KNOW I've seen the larger substitutes up there in various places (probably near Fort Frances or in Atikokan) but I can't recall specifically where.  If you're headed to Atikokan, maybe call Walt's Dry Goods???

Jimbo   8-)