Hey, I'm not too sure about wood properties, but I'm quite sure if you're gonna go ahead with black palm, chances are you should have the glass on the back.
If you wanna cut the risk, try adding the phenolic as an I-beam right through the center. I'm adding a 1/4" phenolic strip down the center of my grey actionwood riser, with another 1/4" strip of the same phenolic as an accent just half an inch from the back of the riser. That will definitely support the limb pads.