When I'm introducing birds to one another, I will put them in a pen next to or along side of the established bird(s). This gives everyone a chance to get to know one another through the fence and work out any issues. Usually, it is the hens who are hard on new hens, but I have had a roo be not so nice to new hens also.
Your idea above of seperating them is a good idea, IMO, and for safe keeping at night you could put roo in a crate and the girls in the hutch, or vice versa.
I use cat carriers/smaller dog crates inside of bigger pens or enclosures often to insure the safety of which ever chicken that needs it. It usually only takes a few days and when putting everyone all togther for the first time, most chicken people do it at night while the birds are sleeping.
Then the birds "wake up" next to each other and it is not as much of a shock as suddenly there are new birds in broad daylight.
The crate could also be helpful to use if later you find Mr. Roo has one particular favorite hen who is loosing too many feathers from his attentions.