i will add backing plate to stern cleats
They are already positioned properly in deck
only, and fittings substantial. They will not pull out but thru fiberglass
, in real extreme force, i expect.
I will not have JDS but lighter version of that using 20mm nylon rope
and add/remove weights/wraps as per conditions. Will use starboard winch
to adjust length - active storm tactics.
I would not use balsa sandwich as not strong enough & you risk water
intrusion and subsequent rot
and further degradation of strength.