Thanks for your advice and the others also. We are going to do just that, we have some leftover 1/2'' hardware cloth. May put some on the area around it so there is more to reach thru. The way the 2x4 wiring is, the chickens can pretty much lay against the fence as they sleep, so an added 2 inches or so will help.Raccoons are great climbers. They could easily do exactly what you are worried about. I would definitely cover any area the chickens rest near the fence with the hardware cloth. Just doubling the fence won't do it, as it won't make the holes small enough to keep their arms out. And if they can grab it, it's dead.
Or, the 1/2'' hardware cloth may make it easier for the 'coon to climb!