Not unreasonable ideas. Similar to some of my own thinking. You've added the pivot, where I had been considering just flex. Easier to actuate, but without any spring back to neutral. As with the TRAK system, though, I wonder how much rudder action can be had by shifting gunwales, as opposed to flexing the keel line.

With regard to flexing the keel line, I've considered running rods along either side of the keelson, where one could be lengthened (and maybe the other shortened), similar to adjusting the neck of a guitar.

: I like the thinking exercise. Perhaps a tube (Yost style) construction where
: the gunwale tubes aft of the cockpit are able to slide into one another.
: Then the deck ridge (center, topside) aft is a single tube which could
: pivot via a pin at both ends. This deck ridge would keep the overal length
: constant while allowing the gunwales to expand and contract. Now the hard
: part... foot pegs that pivot with cables attached via pullies to mounting
: points on the gunwales 3/4 of the way down towards the stern.
: Not much extra added weight. Just a thought, feel free to shoot it down.
: Tim