We have this F16 build going and we are just about to install the chainplates in two hulls. Building plans specify gluing in the chainplates, which I am fine with. Will use epoxy thickened with collodial around the fitting where it exits the ply deck. Then use marine sealant on top again. Not perfect but at least no open wood for water to seep into.
My first Tornado had the chainplates bolted on with bolts penetrating the hull skin + backing plate. The original ply backing plates had rotted when I got the boat so I replaced them. Quick and easy fix, but the best would have been to avoid the problem completely. Now I would have drilled the holes oversize. Filled with thickened epoxy and re-drilled the proper size.
Next boat will perhaps have carbon chainplates which is a different story.