Howdy, Yeah see pat's reply. I too have read that the strongest fibers in the boo are in the very outer layer, just under the rind. For greatest strength, I try to keep those fibers and discard the rest ( of the boo) as much as possible by making the backing as thin as possible. That means knife sharp edges. The thickness in the middle will depend on how high crowned the boo is. Note!! That works well for use with dense belly woods. For less dense woods, the boo can be too strong. When backing wider bows of weaker wood, I have had good results with a thicker boo, that is then trapped to reduce strain on the belly wood.
Ron