Can you use the bow eye and transom plastic gudgeon slot somehow? I like Sean's suggestion but you definitely would have to poke through the plastic and have backing washers. There are already holes in the boat at the drain plug
and daggerboard slot but may not be that strategically placed.
If you could find where the bow eye comes through to the interior
and use the end of that for one attachment point and then find where the gudgeon system on the stern is bolted through and extend some of those bolts you might be able to use those two places plus the daggerboard slot and have a three part sling. That's it for my suggestions. Good luck in your project