Fortunately, my friend and neighbor Chris is a long-time sailor and boat builder, and his current project was at a stage where he could easily move everything over to the side of his boat shop. He very generously offered the use of his shop to me for two months, including the use of all of his tools. He lives right across the street, and given the helaciously wet and cold spring we experienced, I was extremely grateful to have access to his shop.
Apparently our boat was filled with compost in places (hard to believe this mess used to be wood!)
The base of the cap at the aft end of the centerboard trunk was so rotten I could jam a screwdriver about 1" deep.
More rotten stringers.
After using the sawzall on some of the structural members, I had a much better (and far more horrifying view) of just how rotten the wooden insides were of this fiberglass boat.