I have a 78 Catalina 27 and I'm mounting a outboard on center line of transom.I had an aluminum extension made that kina looksa like a pyramid with the top taken of, going from a 13 inch square, which will be bolted to the transom, to a 8X9 inch area that will be bolted to the bracket. (I'm guessing everything will weigh 140-150 pounds including the engine.) On the inside of the transom I have have a 13 inch square sheet of aluminum to distribute the weight of the engine, etc. I was also planning to sandwich a similar sized square of 1 inch marine plywood on the inside of the transom as well.Will that be enough or should I reinforce and glass the entire transom?Cheers,Mo