On my 1982 H16, I have had to remove the plywood from both of my transoms, replace it with multiple layers of fiberglass cloth and resin wrapped around edge, install access ports and install SS thru-bolts, fender washers and nylocks for the old style gudgeons.
The plywood in the transoms eventually will get wet and then swell and rot, which causes corrosion of the aluminum plate and stress on the gudgeon bolts. (Hopefully, Hobie will someday find a better material to use in their transoms than plywood).
If you decide to either tap the aluminum plate with larger diameter bolts or install access ports with thru-bolts, make sure you seal the holes in the transom so water does not leak in and damage the plywood or aluminum plates.