: It has a large open cockpit for easy entry and exit. An open 'Well'
: behind me sized for a cooler or milk crate for storing 'stuff'.
: Flat rear deck with thin plywood under the skin around the well
: and cockpit sides. That way I can attach pad eyes for bungees,
: rod tie downs, rod holder, what ever I find I want or need. I
: will reinforce these areas with small blocks of thicker plywood
: underneath for the screws.

When you skin a deck which has square-cornered openings, as you have in the back of your cockpit and the "well" You end up cutting the fabric of the skin at a 45 degree angle to fit it into that corner. The technique works, but it doesn't give you the strongest of corners. Why not eliminate some of those corners? Make your cockpit and well as one single opening. If the back of the well is curved, rather than with square corners, you might get away without slitting the fabric at all. Rather than using thin plywood for your deck you can use a solid board between the paddler and the well. Insert it after you put on the skin.

Steam bend a 1x4 or 1x6 to match any deck curvature and it will not only be a decorative element, but it will serve as a structural deck beam, replacing the single thwart usually found in roughly that position in open canoes. And, it will be a very strong base for attaching bungees. You might even do some decorative work on it with a scrollsaw, or just drill some holes, opening areas through which you can pass cords or bungees. With a wide, thick deckbeam providing all the structural support the center of the deck needs, you can use very thin stock for framing the rest of the deck--all it is going to support in the deck fabric, and maybe serve as a surface to drive staples into if you attach the fabric that way.

How wide are you going with the beam. I can't read it on your drawings.

That tarp material Yost uses is 17 ounces. It would be another option, and probably as strong as you'd want. Easy to patch, too, if you get a small puncture from a snag in those streams. And you don't have to paint it. The boat would be in the water a week sooner!

Just some thoughts

Good luck with your project.

PGJ