I wonder if there's any way to cram 6 days' worth of food into the Bare Boxer?
You would have to get pretty creative.
You can probably get your six days into a Bearikade Scout, which is not much bigger or heavier, though. It's rated for 5 days, and BPL folks have reported the Bearikade ratings somewhat conservative, so you may be able to cram 6 days' food in there.
Scout is same height, 1.6" bigger diameter, and two ounces heavier. Of course your wallet will be $155 lighter with the Scout instead of the Bare Boxer.