OK, here goes, just the facts as I have made a bunch of bamboo backed hickory bows.
Make them the same size as you would make an bamboo backed osage. I like 1 1/4 wide, glue in a couple of inches of reflex and no need to trap the limbs. You will only get frets if you do a bad tillering job and hinge a limb, hickory is tough stuff.
Be sure to thin your bamboo to a 1/16" edge tip to tip.