Excellent tests. I would agree that the likelihood of submersion, due to tipping of canoes or things just falling out is pretty good. More so on rivers than lakes perhaps. In any scenario, the last thing you want is a wet sleeping bag or clothes, so its good to test those situations out. It would be interesting to try the submersion again, going more methodically, and perhaps in a bigger tub, to see if just being submerged, versus forced into a small space, would lead to water getting inside. Perhaps your assistant could take it in the bathtub?

In 99% of the scenarios its likely to face, seems like it would work great.