How thick are those osage boards that make the limbs?
I think you have enough length as is, but not any to play with, and the added little lam of ipe might be a good idea. But if the osage is thick and the hickory backing is added, and you work down fadeouts from the limb pockets out, then the limbs might not really start bending until an inch or two beyond the limb pockets. That would be correct, in order to relieve the stress at the fulcrum point of the limb pocket, of course, but then, do you really have enough limb lebngth?
It does help that it is deflexed. In R/D backed bow glue ups I do this very thing, and the deflexed portion of the limb off the handle only bends a little bit. If you can pull that off, you'll be fine, esp with perfect osage.
Consider putting the ipe UNDER the hickory, like a power wedge version of a power lam?
