Thanks for your responses.
The easier it is to get canisters, the less we have to carry. If I verify that canisters are available at the Tooth of Time Traders, we can check the advisors' lounge. With luck, we might be able to scrouge all that we need :-)
Likewise, if they assure us at headquarters that canisters are available in the backcountry, we can run closer to the edge. I just don't want to be eating cold, dry Philfood while I'm there.