I just redid my 1974 reinell with new transom wood. It has a stringer drive, so im not worried about pressure on the transom. All I did was got a roto zip and cut around the edges of the old wood. I pried it out and chiped out all the bad wood. I painstakingly dug out all the mulch that was behind the stringers. After I cleaned it I mixed some poly resin and dumped it down the gap. I had to make some dams with clay to keep the resin level. After the area was half full I shoved a fiberglass mat down there and put more resin on top of that untill it was level with the stringers and floor. Then I got some more poly resin with cotton fibers to adhere the new ply wood to the transom. I also adhered it to the resin that I poured behind the stringers and floor. After clamping the wood to the transom by another sheet of ply on the outside and bolted together for 7 days I fiberglassed a layer of fiberglass cloth to the entire inside of the transom, then I filleted all the edges of the transom, including the floors. Put a new coat of paint on and now it looks like new. Anyone think this will work? 
