You could start with this idea. Make the sides a bit higher and then don't deck it. This was meant to be a one man white water boat.
It is a hell of a good fishing boat too though. I've had it going on 4 years now. Best thing I ever made in many ways. The only drawback is not being able to row and fish at the same time. So it is dependent on stopping a lot.
The "plans" for this boat are not finished. All the dimensions are there but I haven't finished writing the step-by-steps yet.
https://localhost/mrb/?page=Driftboats/OneMan
The Don Hill skiff was his creative way of using the left over strip of 1/4" plywood after cutting a "high side" side panel out of a 4x16' sheet.
So. You could also use the plans you have and just make it shorter. Chop 1-1/2' feet off both ends to end up at 11' long. Make the two transom ends a bit bigger. You'd have to wing that part. But it wouldn't be hard.