hope this makes sense. We use to use a similar idea on moored wayfarers at the centre I worked at. Get a block of wood that is larger than the hole at the top of the transom. Drill a large hole in the middle of it and through this attach a mooring line. Once the bow is secured, the block is turned, pulled through the transom and then placed over the hole. The added advantage here is the block and line could be left attached to the buoy making for speedy pick ups.
Hopes this makes sense, unfortunately I don’t have pictures.