I have been busy working and haven't spent as much time working on this as I want to but still managed to put in many more hours on the boat!

I used a slow hardening penetrating epoxy to treat all the dry rotting stringers. ( wow that stuff works great!) All the stringers where very brittle and after treatment they are more solid than new wood!

I cut out and made the transom out of two 3/4" marine plywood pieces laminated using Epoxy Resin and stainless screws. I sandwiched fiberglass in between and left it hanging out the sides so it will bond with the sides of the hull. Then used two coats of slow cure epoxy resin on all sides.
After that cured, and a few dry fittings and trimming, it fit nice and tight.
I made three quarts of epoxy mixed with milled fibers and fumed silica till it was like a peanut butter consistency. After washing the transom area down with acetone, applied it to the new transom and boat all around the sides before setting it in place.
After that cured (24hours later) I glassed the bottom in, using 20 oz fiberglass roving.
Also laminated a block of AZEK to the bottom of the hull and drilled through the hole for a water pickup for wash down and live well.

I am starting to add new marine plywood to both sides of all the stringers after treating them again with slow hardening epoxy resin.