Ok... so time for an update! Going back in time to 24 June 2017. The next section of ply wood laminate was cut to size from paper templates, grooves cut into the layers about half depth to allow for easier bending to match the deck curve, pre-coating the one side and deck area to ensure a good bond, mixing up a batch of resin/chopped glass/silca to make the adhesive, applying said adhesive and then positioning the section of plywood in place and weighting it down with some hefty persuasion. Left it like that for a few days, removed the weights, cleaned the surface and applied the first layer of CSM to seal the wood. Looked all good so far and the deck is really starting to retain some stiffness again.