A few notes about the design changes. The four pieces of plywood "just" fit. So close that I didn't know if I had enough room to create the transom doublers and other odds and ends pieces--not to mention any room for even the smallest mistake.  My other concern is I wanted to slightly increase the displacement. I ended up increasing the depth to 5" and shorted the length by 10% so it's now 12'6"

Other progress. I had many stem options including just stitch and glue, an inner stem, two part stem or a rabbited stem which is what I'm going to try.

Below shows the stem pattern.

On each side of the stem, I routed a 1/4 deep rabbet and then chiseled a bevel angled for each plank.