If you don't want to attach the hull and deck at least put spreader sticks in each so they don't close up while you're working, which they will. With slightly bigger spreader sticks than the width the hull/deck is now you can gradually return them to the proper width, once they get fairly loose put in bigger ones until the hull/deck is the correct beam for that station. Heat helps, putting it out in the sun will help to speed the process along.

Bill H.