A carbon rod would be plenty strong to hinge a rudder. However, I'd be concerned about the rod wearing down by the friction of the hinges, dirt, etc, rather than the hinges being worn by the rod. A lot of that depends on what the hinges are made from. If they're nylon, I don't think you'd have any problems. If they're phenolic, as in the Integral, there could be a problem but I wouldn't expect an instant catastrophic failure. The wear would be gradual, if at all, and something you could easily spot if you inspect it on a regular basis.

Verne Koester