Sassafras, in my limited opinion, is one of those "born to be a D" woods. I tried maybe half a dozen bows from sassafras over the years- I had three D bows survive, one come very close, but absolutely every stiff deep handled bow I made was a failure!
If backing it with hickory, you remove the biggest issue with the wood, it's low tension strength. Just make sure you crown the back and leave the belly flat. Kinda like a reverse ELB. Sassafras, at least the stuff that grows here, seems to be low in elasticity. Low stress designs, and especially low draw weights, seem to fit it better.
Good luck!
