I went to the lumber yard and bought a 2' section of 8" diameter SonoTube (used for forming concrete columns), which I cut into 14" and 10" pieces to simulate the Bearikade Expedition and Weekender, respectively.
So now I can test "canisters" in packs, as well as determine just how many days of what I can get in which.
But, for a JMT trip, I got 5 days into a Weekender with a little room left over. Freeze dried, even when repackaged, is bulkier than dehydrated (which I had) so it is hard to guess. You Might get it done.