Have you talked to your neighbors? I have a loud hen and that's what I did. I was worried about the response but turns out she wasn't bothering anyone (except us, as the coop is 30' from my bedroom). Asking directly could backfire but it is what I would want a neighbor to do so it is what I do.
As for controlling it, I would try:
locking them in the darkened coop until as late as 8 or 9 am, cover all cracks and crevices from light BUT maintain ventilation.
if they can't free range all the time, consider not letting them out in the morning, as this is when they are noisiest and they will start to demand it if it becomes their routine. let them out at the end of the day instead. or it is possible that you'll find they quiet down if let loose...but probably until you lock them up again. it may take experimentation on what works but try to work toward a consistent schedule.
give them treats - cabbage, scraps, an old stump, crickets, a pile of leaves. try to give them more space if you can. keep them occupied with things to climb and perch on. in the end, though, the dominant hen is usually loud in the morning.
