Ive thought about this idea myself,a 60" span model which i have on plan,uses ali tubes for pivot,and i agreed also,this would be not a sensible option due to flying loads,but the designer had built it this way with no problems,i myself have my doubts!!,and i dont think i would have much faith in it!!
I am still thinking of using piano wire,i have an eindecker 60" span electric,that uses a 10swg pivot,running in a brass tube bearing,and thats working great,it might be worth looking at that option still,and its really strong!!.
But i expect others will have other ideas!!!

Eindecker