Sorry, no pictures until its done. I just don't have enough time!

The Paul's description matches your request on how to make the cockpit area like a sit on top, my boat is more like a traditional kayak but with more foam.

My feet are only size 9 and I planned on shortening the pedal arms. Long legs would pose a greater challenge, because there must be enough room for moving legs under the spray skirt.

The slot is pretty big, but the walls for the slot are made of 1/16" balsa w/6 oz glass both sides, so (hopefully) the water will not rise above the wall. If water is a problem, I will fill any empty space with 2 part polyurethane marine foam.

Any suggestions on steering would be appreciated. It would be nice if leaning were the only means needed to maintain a course. For steering, the plan is to test in the following order:

1. Use traditional and greenland paddles. A forward stroke may not work well because it's like trying to pat your head and rub your belly at the same time.
2. Make hand paddles and use them like cross country ski paddles.
3. Add a rudder.

Thanks for tip about the bent arm, I'll be sure to carry spares.