Well, I only have 3 chickens, but their run is pretty big for them, I'd say 6 ft by 15 ft so they have alot of space to play. I also have three perches in the run and I always see them jumping on and off during the day. Some people hang a suet feeder with goodies in it for them to jump up and peck at.
I also have a tarp over a section of it so on rainy days they have a dryish spot to hang out. How about a plastic bin for dry sand for them to dust bathe in?
If they are pecking and eating feathers, also consider upping protein in their diet. Since it is a polish getting pecked, it may also be a dominance thing where the polish cannot see to get out of the way before a peck. If that is a case, a haircut or a trim or a hair tie to keep it up so she can see may also help out.