Looks good.
I haven't used Birch bark for several years but when I did harvest some bark I took it from large trees that would do 1 entire limb from handle to tip, I think at least a 12" tree is what you need. I have cut many Paper Birch trees and I can tell you that they don't all have bark suitable for backings or canoes. Some trees have thin bark that is brittle and some trees with thick bark that is flexible, the thick bark can be more than 1/8" thick. The brittle bark you can actually tear fairly easily across the grain but the thick flexible bark refuses to tear even when it's thin, it just stretches.
