Using the other side as a template, I would use a couple of small padeyes to anclor your bungee. A simple knot should work with a little heat treatment to keep the bungee from unraveling and set the knots.
Use an identical eyelet post as you see on the other side.
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[/urlFor a forward support, I like an an arrangement like this:
In your situation, perhaps a small plexiglass or plastic wedge under the strap to mimic the bump out (my strap comes from a small stainless chainplate), bent at the top, kept short and rounded so as not to catch the paddle or snag you if capsized. What I like about this strap arrangement is, you can temporarily set the paddle down without bungeeing it if the water is calm enough.
A little dab of silicon calk at all your through hull fittings should keep the water out.
