I know very little of rats, since I'm a beginner myself. I've recently created a thread about raising a male and a female rat together, since I discovered the two boys I bought were actually a couple.
Some users said that it'd be better to neuter the male, since it was an easier and less risky surgery. But a certain user also said that if I decided to neuter the female and not the male, the male would still try to mount the female, and it could cause her pain.
But I'm sure other users could answer your question with more certainty. xx
This tends to work well, the thing about males mounting females isn't useually a problem as despite being smaller the does are quite capable of telling the bucks to back up. I've seen a 300g doe terrify a 700g buck when he expressed an interest in mating and she repeatedly kicked him in the face and told him off. Generally bucks aren't that interested if a doe isn't on heat (which a spayed doe wouldn't be) and once they are used to the doe being around wont bother her, especially if she tells them to back off.
I currently have 3 spayed females and just introduced an unaltered male into the mix. I had the girls and chose to spay them because they are less likely to get mammary tumors and pituitary tumors. I have lost almost all of my rats to pituitary tumors or mammary tumors and I just wanted the cycle to end. They're almost two now and healthy. The boy tried mounting them in the beginning, but it has really calmed down.