Have done BL with both hickory and bamboo backs. I once bought a huge plank of it off ebay for very little and made at least 5 BBBL and HBBL recurves from it: large recurves, lots of deflex. Nice shooters.
So, the key is the stiffness of BL. It is so stiff that, even backed, making a nice wide limb with a thin backing helps. a lot. It just ISN'T osage or bulletwood, so it needs to be thinner, hence wider, or longer.
I am in the camp with Baker concerning backings that says NARROWER is better than THINNER for backings, but with BL, in order to avoid frets on the belly, the total limb thickness on a 68" X 1.75" wide bow is only barely nudging toward 1/2". So, you really should trap the backing and make sure the belly lam is still 2/3 of the total.