Dear DeaDrift,

Cut a piece of plywood to fit between the bench seats. Taper the edges of the plywood so it fits the shape of the hull's sides. Screw sections of 2 X 4 on it to span the open area underneath. Make sure it fits between the ribs on the boat's floor. Bevel the edges on the 2 X 4's so that it is as flush as possible with the sides and bottom of the boat where they make contact.

My buddy did this with his flounder fishing boat and it was stable enough for both of us to stand and cast. He could even stand up and run the outboard in 3 foot seas all day long. It took him about 15 years and two outboards before he beat all the rivets out of that old Mirrocraft.

Best Wishes,
Avalon