Ask yourself where is the structure holding the sides of the boat open? It's not the minimal ribs that don't go up very high. It's not the gunnel cap that's formed by the curve, not for the curve. It's the seats doing all the work. You don't even have strakes stress stengthening the metal...
That is one of the thin skinned hulls, I had one for a while. To do a seat removal on that (personally I wouldn't) I would suggest making new ribs the full width of the floor, laminate layers of plywood or an all aluminum construction. Think Jigngrubs braces going completely across the bottom of the hull and up the other side. The corners of the floor will be the highest stressed point on the hull. The curse is you will be rebuilding the hull adding lots of weight to make up for the strength it never had. I wouldn't do it, find a thicker hull to mod.
Those hulls were designed to be thin and lightweight so the underpowered outboards could move them back in the day. Look at the sales pictures from back in the day, couple rods, a cushion or two to sit on and a basket lunch for two. That was the manufacturers intended purpose.
Jamie
