It's fairly important to keep your boo thin. I've seen numerous instances where folks didn't and the wood on the belly got thin trying to reach weight. This makes it more likely to overwork the belly surface resulting in compression issues... although this is a little less likely with ipe... it's so tough.
The bulk of the material on the inside of the bamboo can be removed by any of several means... bandsaw, jointer, edge sander, hand held beltsander, hand plane, rasp, or whatever you have. But to reduce it to final thickness, it's hard to beat a toothing plane for this job. I use it on every one of them and wouldn't make a bamboo backed bow without one. It leaves a perfect gluing surface for gap-filling glues like Smooth On, Unibond, etc. It's use is gone over in detail in Dean Torges' DVD "Hunting the Bamboo Backed Bow". He even tells you how to make one if you want to save some money. That dvd is a valuable resource for the bowmaker working on such bows.
Using the toothing plane, i lay the bamboo belly side up, clamped just on one end, supported between the nodes with 1/8" thick rubber strips to keep it from pushing down, and go to town with the toothing plane. I make the bamboo 1/8" at the handle area and about 1/16" at the tips. It does an excellent job, is easy, only takes a few minutes. That plane is the best investment I've made out of all of my hand tools. Check them out.
