I haven't had mites , (that I am 100% sure of, I might of had one case with out knowing,) in my 10 years of rat experience, but I have some quick answers from what I /do/ know.
My first rat had flees, and he got depressed quickly when I stopped taking him out. I took him out anyway because I couldn't bare to see him sad. I took him out anyway, and played with him. With rat flees, they are large and obvious, and he was completely infested twice. Rat mites and flees don't transfer to humans, but can sit in fabrics. I never had carpet, or mites, but this is what I think would happen;
The mites could transfer to the carpet, as well as your cloths, but they can't live without the rats. I think that because they are being treated, you can, (and should,) still take them out and play with them, but the carpet might be an issue. They won't be able to live with out the rat, but unfortunately, from what I have read, they can live from 10 days to 3 weeks without the rat to feed on, but this isn't the end of play time.
What I would recommend, would be putting down a bed sheet and put play toys and climbs and interesting fun things on the sheet. That way, at the end of play time, you can throw the sheet in the wash, and an average dryer cycle will take care of any pests left on the sheet. If you take out one rat at a time, and give them interesting things to do on the sheet, it will make it easier to keep the rat on the sheet for play time.
After the treatment, they can play where ever they want, obviously, but keep an eye on them. Also, clean all of your bed stuffs if they play on your bed, and throw pillows and other fabrics that cant be washed in a dryer if they play on your bed. I find limiting rats to a bed for play time makes them easier to keep track of and make sure they aren't getting into trouble. They also love playing under blankets, and it's easier to clean a few blankets then a whole carpet.
If you can get a carpet steamer, (which I understand if you can't, this is more of an option for the wealthier rat owners,) steaming the carpet will kill mites on the carpet.
If you let your rats free roam around your room, (which I don't recommend because they can hurt themselves by chewing on wires or other harmful things in your room, as well as chew on things you don't want them to chew, like the carpet it's self,) keep your door closed so they stay in your room, and you need to 'rat proof' everything, (which is hard because they are good at chewing and destroying.) Also, free roaming rats means poop and pee can get anywhere, and, (especially because you have carpet,) can be really hard to clean, and they will stain and chew the carpet.
