On the starboard side you have only the forward bulkhead, unless you build yourself a removable one to act as a longitudinal bulkhead.
Connie, Very interesting... Jerry must have made a lot of mid-production run modifications. Like yours, my M15 has the large enclosed cockpit locker to port and a shallow tray cockpit locker to starboard. The port locker is enclosed by a forward and a longitudinal bulkhead; however, there are no bulkheads on the starboard side. The area under the starboard cockpit is open from the cabin to the transom, yet accessible only by very small, flexible, non-claustrophobic people. I attached a small block with a continuous loop of 1/4-inch line to the transom at the aft end of the "cave", sorta like a horizontal flag halyard. I tie containers, trays, supplies, etc., to the line and haul them in and out of the space as necessary. BTW - I picked up a socket for the Forespar tiller extension the last time I was at WM. Now that life is approaching a somewhat normal pace again, I may find time to install it. Joe Kidd M15 #207 "Poco A Poco"