Old tilt-in windows

Hello, new here to the forum and hoping for some advice. Hopefully someone has seen and dealt with a similar issue. I am converting a lean-to addition to our barn into a coop and the windows are all the classic barn lean-in or tilt-in windows that aren't permanently affixed to the frames. As barn windows go, I love them but I'm not sure what the best method is for chicken-proofing them. I will definitely staple some hardware cloth to the outside to keep critters out but I am also concerned about the chickens roosting on the inside and pooping all over the open windows (leaning in) which could be super messy. I've provided a picture of what the lean-to looked like before it was converted. It looks much different now. I'll post the updated image in the cheap homemade coop section soon. Anyway, the windows have been all fixed, painted and replaced but it should give you an idea of what kind of windows I'm dealing with. So I thought about building a slanted "roof" over the windows to prevent roosting but I feel it would sacrifice a lot of the ventilation. Or what about a vertical chicken wire fence around the top? Better ideas, tried and true? I'm open to them.