While away from this project for a couple of weeks I decided that the hardpoint installed for the rear center seat support was too weak being simply mounted on top of he floor as directed by the manual. There is quite a bit of stress on this hardpoint resulting in excessive flexing.
I removed the hardpoint and fabricated another. The new one is installed by relievieng the top layer of glass and foam. I used structural epoxy to glue it to the bottom layer. Then, filled in the remaining gap with a mixture of epoxy, flox, and cabo. Covered with 2 bid and peel ply.