Can you describe your Sunfish set-up? I still have mine from my youth and would love to do some kite-boating. Photos or drawings would be great too if you have them. Thank you.
I just got the largest eyebolt you can crew into the top of the daggerboard (you have to pre-drill in order not to crack the board). If I am not mistaken it was a 3/8 x 4 bolt.
I also drilled a 1" hole into the dagger board just below the keel and drove a peg thru it in order to avoid the kite pulling the board out.
Than I tied the chicken loop of my kite to the eyebolt (I guess a shackle might have been a more elegant solution, but with a piece of 1/4" of nylon rope you can adjust the length of the setup and thus the distance between bar and deck), sat on the deck with one leg on each side of the shacke (ass apwind) and had a buddy attend the tiller/rudder.
This setup works well, however I would suggest attaching the kite further back on the center line of the boat, in order to have it turn into the wind when letting go of the tiller.
Make shure the peg is properly seated or your attachment point is sturdy enough to be loaded with the complete weight of the boat.
Have an experienced kiter and sailor at the helm, things could go wrong quickly if you don't have a good teamwork on board, specially with our setup that had the tendency of turning out of the wind on a loose tiller.