Looking good.
I would make sure that plate is at least 3/16" thick. You could also remove a little more of the forward sealing surface of the hull if you think it would help with room to work in there. Before you glass that plate make sure you add some glass to the inner hull where that plate will rest. I realize the torn hull will be beefed up but the other hull should be beefed up also. The most important thing is to get good adhesion. Sand well and pre wet the areas with epoxy before adding parts or glass. When you get ready to put that tang in bed it in a blob of epoxy putty to prevent any voids. Mix mill fiber in to that putty so it's strong. If you have any questions you want to discuss feel free to call me.
You can just brush some gelcoat over the repair area and do the fine finish later. You should cover the epoxy to protect it from the UV.