There's skin on frame traditional and modern. Modern having plywood hull shapes motticed in to a frame. Here a bulkhead would be easy. Traditional building presents lots of problems with leakage around the outside skin and mating the ribs to the gunnels etc. A hatch would be easy. Any plastic Beckson type or even a wood one with 2 frames sandwitched between the skin and clamped with adhesive.

I consider skin on frame a much more dangerous craft especially in the cold water (even with float bags) for that reason. An enormous amount of water enters the craft even with the bags and it's hard to drain. I have one and use it in the warmer months but feel really secure back in my stripper with bulkheads in the winter.