I am building a Great Auk, and plan to make a keyhole cockpit, like Nick describes in his shop notes on the Guillemot web site. Do I need any additional reinforcement, or is the fillets enough? I am using cypress for strips. Also I could use some dimensions, like how wide and long and placement in the cockpit. I can figure it out, but would like the input from the board, especially from someone who has built and used the keyhole cockpit.