JTurner;
google Seminole dugout canoe, and go to the "Seminole Indians with dugout canoes, in Everglades National park, 1921. It shows the style, they made. You can see how wide they are, and how many people it held, and the bow and stern style. Personally, I would go at least 15' or more. Is this just going to be for you? Are you planning on putting stuff in it?
Some of the Creek style dugouts, had cross sections that were left in to strengthen the sides. They were sort of seats, not that wide . They were just a section or two, that spanned the width of the canoe, and were lower than the sides, and somewhat " U " shaped. Do you have any marsh areas where you live? You could use it on a hill, in the snow......
Traditionally, these were poled, but they also had some long paddles, they used while standing. Sort of like the African natives in their log canoes. If you use a pole, I might suggest that you use a forked end, or make a hinged " Y " section at the end. That way you don't sink in the mud so much, and when you pull the pole up, the " Y " end closes, so as not to create much drag in the water. Also go to State Library,and Archives of Florida. They have excellent pictures, of dugouts, and the various styles, and different freeboard heights. You can get some great ideas on how they were made. Hope this helps. And good luck. You can cut to length, the log, and then flatten one side for the bottom, and shape it, and and turn it over, and flatten the top, and start to hollow it. Look at the pictures, they have a lot of pictures, that show basically how they were made. The poles were a combination of push pole, with a paddle blade. Take lots of pictures.
Wayne