Simple solution is to place span strips at each form location. Measure the width of each form along the sheer line, cut strips and install them in the hull in the same locations the forms would go. The strips will hold the hull to the proper shape. Place the strips a quarter inch below the top so they will not interfere with the addition of the deck. You will then be able to use epoxy to tack glue the deck to the hull. Then the strips are easy to remove.
You shouldnt have to pry with anything if you take time to plane a bevel into the sheer strips. Both deck and hull. Then dry fit the two halves to make sure that the span strips are set accuratly so the width of the deck and hull are of equal widths the entire lenght of the boat. This dry fit process may take some time but it will make the actual bonding go much better.

Robert, Visionary