:DIf you have access to wood ashes, this will help them to dust bathe in it. If it's lice, you probably wouldn't see them on the roost. If lice, you can see big clusters of white at the feather shaft. Either way, the methods you have mentioned should get rid of either.
My Chickens also love...
Wow! That sounds horrid! No idea of your location, but sounds like Northern Red Mites. Clean the coop out. Top to bottom. Bleach what you can. Let it dry. Wear a mask. Spread food grade diatomaceous earth around every crack, crevice, nest box, on the chickens, wherever you can. The DE...