I've done the research on it, there's a lot of hickory backed red oak bows out there. 3 rivers even sells one. I'm aware that the backing needs to be thin and the back should be trapped. Going in favor of this design is the very wide flat limbs which should reduce chrysal issues if I do my job as a bowyer correctly.
Now, I do know that there is still some risk mixing these materials like this. Truth is, the bigger risk to this bow at the moment is me making a major mistake. I got the best red oak board I could, but it's not super great and a strong backing is mandatory. Yes, I could have sought out a better more expensive piece of wood, but when you factor in the odds of me screwing up, the cost benefit analysis of doing that puts it way past the point of diminishing returns. It would be nice if this bow came out perfect and lasted a life time, but that is not in my realistic goal set at this time.
I would maybe go to 3/4" at the base of the levers, but 1" seems way too fat to me. Hell, the handle, where the stress is much higher, on my current bow (modified since its thread) is only a little over an inch thick. On my current bow I've also gone for 3/8" tips and that seems to be the butter zone to me, if not too thick still.
Also, I do have a pretty dang good idea how thick the limbs need to be since I've already made a fairly similar bow. Properly heat treated, the treating should extend quite a ways into the wood (i.e., not just scorching the surface). Sure, it won't be perfect and I know that I won't be able to apply more heat treatments during the tillering process since I'm going to glue up a backing, but it should help and also give me a bit of reflex at the very least.