I've left food in a canister inside a pack at Lower Trail Crest numerous times with all the zippers zipped up and have had zero problems.
Tempting fate again I see.
I've seen packs at Trail Crest with critters having fun in them.
I'd definitely put the cannister outside the pack -- just in case some dumb marmot couldn't tell the difference between a pack with food inside versus a pack with a canister inside with food inside.
