Wow, not sure how I missed this thread, awesome job! On the seat question.....I had found an old chestnut that had been fiberglassed over. I think it was a pal, but hard to tell. The interior was still original, and the seats were wooden slats. I was told that these were options for bush canoes, because they never needed maintenance. They were bolted directly to the gunwales as well.
I really liked those slat seats, found them quite comfortable, and they were always dry too, and actually quite light.