To reduce marina fees, what about shortening the length as well as the width of a folding proa. A 40 foot leeward hull appears to have about a 28 foot weather hull. If you separate the LW hull into two 20 foot hulls that are connected at the inner ends, each half could have one beam that pivots the hull to lie alongside the accommodation hull in a similar manner as that of the Quorning Boats Dragonfly. Each beam would only need two pivots rather than the three of the Ex 40 which would balance the need for the connection between the two LW hull halves. Folding and unfolding could be simply achieved using warps to each end of the hull half.