I "wonder" for the hiders, if a couple of 5 gal orange Home Depot Pails with those snap-on/screw down lids wouldn't make good a viable alternative for those small blue barrels?
Smaller volume but might work for solo paddler.
You could remove the metal handles so they lay better in a pack.

If they truly make bucket waterproof, you could add a rope/rock anchor and drop offshore in hole if you thought Yogi might be dropping bye.