My ladies aren't laying yet, but he minds his manners most of the time.
He is not a rooster, he is an immature cockerel with hormones probably running strong. You do not have hens, you have immature pullets. How old are they? It can sometimes be hard to watch chickens go through puberty but usually it's a lot harder on the person watching than it is for the chickens. Eventually the pullets and the cockerel will mature to the point that they act like mature chickens but until they do it may look bad to you.
Many of us that keep roosters let them grow up in the flock with the girls. I haven't done a poll but I'd think a strong majority of us do that. Some people can't stand to do that, they think it is so horrible for the girls. There is often violence involved so it is possible there could be some injuries. You do have to watch what is going on so you can take action if it is needed but I've never had a pullet injured when they go through this. Some people on here say they have.
I've been supervising their free ranging from afar so me being around might be making him behave
I can't tell by what you wrote what behavior you think is so bad that it warrants isolation. He's probably behaving exactly as he should as an immature cockerel with immature pullets. I can't tell but it sort of sounds like he is extraordinarily well-behaved for a cockerel going through puberty with a bunch of immature pullets. You'd hope for a cockerel to behave like that. Or maybe you are not giving him a chance to do what immature cockerels with immature pullets do naturally.
Our expectations have a lot to do with how we perceive these things. I don't know how you expect them to behave. Once the girls mature into hens and he matures into a rooster they tend to settle down a lot, though he will still mate with them. Sometimes by force. Some people can't stand to watch that so they should not have a rooster with their flock. I don't know where you stand on that.
I just don't know what behaviors you are seeing or what you are so worried about seeing. That's part of why this is so hard to write.
I would love any ideas for his winter housing or what you guys think of the hutch!
In South Carolina he can easily spend the nights outside in your mild winters. Your weather is not a problem. The risk I'd be concerned about is predators.
I don't like that hutch. It is not designed for chickens and ventilation looks horrible. You could put a roost in it but he doesn't really have to roost. As you said, he sometimes sleeps on the ground. It may be hard to train him to put himself to bed in there at dark. If you spend money for something, I'd want it suitable to be used to isolate a hen if you need a hospital. That would mean a nest at least. Not sue how big it is but probably something a bit bigger.
If you let him try sleeping in the coop, let us know how it is going. If you don't like what happens don't hesitate to separate him again. But describe what happens so we can maybe help you get through it. I think you need to base your actions and decisions on what you actually see, not what you think might happen.