I have glued in the central seat support spine and the main bulkhead, which keeps it in place and holds the shape of the hull. The stern seat parts are just propped in place to see how they look. Tricky to fit, as everything slopes and the internal corners are very rounded with the epoxy fillets.
I have cut off the first few stitches around the bow transom, just to see the effect. It will be easiest to cut them off when the hull is inverted.