Yes, I can tell you from experience it will promote rot even on a cedar fence. Perhaps you should consider a wire or cyclone fence as support. Yes, you can find Boston ivy at local nurseries. You may want to consider a mix of clematis for fall and summer interest as these do less damage to the wood. You can enjoy the blooms of Clematis Montana in the spring, Sweet autumn clematis in the fall and Jackamani in the summer and cut these vines back after they bloom to let the fence dry out. Keep growing, Marianne Binetti