Fallback to other unlicensed bands like 24GHz or 60GHz would probably work better. The higher frequencies at least retain a compact dish size, smaller fresnel zone, and sharper directionality. That is, imagine hanging several of these optical devices + 5GHz fallback at ~1 meter vertical spacing on a pole. A weather event triggering failover on all optical links could lead to enough 5.8GHz self-interference to kill the fallback links as well. 5.8GHz devices that aren't synchronized in phase with each other often call for 3meter+ separation, eating up tower real estate.