scary rot discovery

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i recently noticed the thru-hull in my bow fish box was a little loose when i pulled the plug to clean it. when i went to open it up my worst fears were realized when i discovered rotten wet wood on the sides. it being summer and me using my boat 3 times/week i did the super intelligent short term idiot move of resealing it to be dealt w/ later in the year. wondering what standard operating procedure is here. obviously all the rot needs to be removed. im thinking: 1-carefully cut out around thru hull in circles til i get to dry solid wood, leaving interior fiberglass intact. 2- patch w/ marine ply. 3- bondo her up. 4-paint boat, which was already going to be my winter project. recnetly had the motor off the transom, was scared about that but all holes in transom were bone dry. checked other thru hulls, same deal. this is an isolated area, hopefully small, but who knows. any insight would be appreciated. this is not affecting the ride at all so its easy to block out but i also want to keep the boat forever so it needs to be addressed.