G'day Pete welcome to the forum, I've repaired a few boats and feel that putting an extra hatch in to me looks a bit odd it also gives no structural support to the deck letting it crack around the hatch. I personally save the bit cutout of the deck,after the repair I glue some divinacell. foam under the deck hole at the same time resin the cutout deck back in the hole. To me it looks much better for not much extra work