Connor,
Do you have any experience with fiberglass? If so, here is my suggestion and a trade we use here in hawaii for marine grade. Buy the 1/2 marine grade plywood and cut and drill to your specs. Then rough grain sand it and layer fiberglass fine weave over it in two layers with the resin. Sand the edges and ream your holes when dry......you're done and have the same exact look and function for a much cheaper price.
If you are feeling saucy, on the last layer, sprinkle sand over the top-coat for permanent non-skid. 100% water tight, durable, and will outlast your grandchildren!
Or, Starboard in brown with the deck skid on it as suggested before. They have a million colors now! Will look very close and most starboard dealers will water-jet your specific cut. Again, not cheap but life-long solution.