Chris-
What was said about ipe wanting to fail where you had an uneven taper made a little sense. It did fail where the boo was thickest, which also means where ipe was thinnest. Regardless, I think I'm better off now.
I should check the thickness with calipers, but I'm pretty sure I'm under .180, maybe close to .125 at the handle and what seems to be crazy thin near the tips. I used the belt sander method, and kept working the boo over it until the thickness was a smooth, even transition to the tips. Not sure how a person would do any kind if tapering jigs for bamboo backing. The nodes are really not even enough to allow that and you'd have to support in between and keep from rolling all at the same time. Being an engineer, I'm sure there's a way. But I doubt it's worth it unless you're selling them in large quantities.