When my birds were little, I used some scrap 4”x4” posts and a 2”x4” to make a short roost. It was only a couple of inches high, but they loved it. I did the same thing for in the “juvie jail” coop for a recalcitrant roo, but his was higher. If you have some scraps, you might be able to make a roost that would fit in the coop.