My rooster overmated my hens last summer, they all had bare backs. As a new chicken owner I didn’t know that could happen. As you already stated, it’s not fair for the hens. My fix was to partition part of the coop and run off with chicken wire so he could see the hens but be kept away from them. It works out pretty well. As long as he can see them and be close to them he’s pretty happy. He will be 2 years old next month, I’m hoping he will cool his jets in the next year or 2 and then can be reunited with the hens
Initially when I separated him, I kept him out in the run only. He was miserable when the hens went in the coop and he couldn’t go in or see them. He made the saddest cry, like a quacking duck. His appetite decreased and I had to hand feed him. Finally we made a window into a door so he could get into the coop and see the hens and sleep under the same roof as them, but still be separated. I’m fortunate to have a really big outbuilding as a coop, so it was easy to partition that off too.
Not sure how old your roo is, but when mine was just over a year old I tried the hormone implant. He was too old at that point for it to be fully effective. It did decrease his mating and aggressiveness, but only for a few weeks. If your roo is young it may work for him better than it did for mine. I also talked to the vet about caponizing (neutering) him but at an older age it’s a very risky surgery since the testicles are internal and near the aorta. I have heard about people caponizing their own cockerels, but in my opinion it isn’t something that should be done without pain meds and anesthesia- ouch!! Since he’s your pet I’m guessing you wouldn’t anyways.