What you folks are describing re the sit-on kayaks seems to be a replication of the old sneakboxes (not sinkboxes, an entirely different animal) once common on Barnegat Bay. Floated in a couple inches of water, rowed, able to slide up on flocks of resting ducks. The difference being that the kayaks are made of synthetics and weigh a lot less than the sneakboxes, even though the sneakboxes were lightweight as wooden boats go.
Still, no one has solved the shuttle-driving problem for floating downstream.
