That's one of the problems I keep haveing. I have plywood. 43x45 inches and I don't know if I want to make one long coop that is short or one tall enough to walk in. Wasted head space for a walk in but easier cleaning. I have a good screen door and some 5x5ft bay windows that could be used for a tall coop. Also trying to find a way to get it done cheaper.
My chicken runs are 6' in front and 5' in back. I've bumped my head a few times, but I've learned to duck. Mostly if I move to the back. 6' is plenty high enough for me.
I think if you look at a lot of designs and use your imagination you should be able to make something. This crate has a back door that opens up completely and I can reach in with a hoe and scrape everything right into a wheel barrow. I use it as a grow out coop, but may use it for a single rooster too.
I've since added a pop hole and 8x6 run on the front. Only problem is getting new chicks to learn to climb the ramp and not go underneath it at night. There is chicken wire behind the lattice. It's bent out away from the sides about a foot or so and now hidden by the grass.
My point being if you build a coop that is easy to clean without going in too often, short would work.