Wow!! You know, I was really hoping for your advice and that's interesting about the breastbones!! Our problem is STOPPING them jumping.. they just seems to want to. And in nature they'd do that too, right?
We don't have rats that chew through feed bins. We have had plastic bins for years and never has a rodent chewed through. We keep things fairly tidy and put a couple of traps in the shed behind the coop.
In nature, they'd long since have been dinner. The original chickens were jungle fowl and they are a very light body bird. The inbreeding to produce a large body that will lay lots of eggs or produce lots of meat has changed all that.
Our highest roost is 3', with deep bedding under it. The roosts are staggered 1' apart and down. But the damage we find to breast bones at butchering time, when they are 18 months old, is nasty.
I know some of our will jump too. And you do offer the ladder. Not sure what else you can do besides block off high areas...
I think we will shift things around with that knowledge.. glad you could advise!!!