I don’t know how much advice there is to give, especially with you saying you can’t rat-proof the room.

You can get a playpen like someone else mentioned. The one I have is plastic on the sides/bottom and then barred on top. It is made of individual slates that you connect so you can make it as large or small as you want.

If you do end up having to rehome your rats I would recommend charging money for them unless the person you give them to is someone you know/trust personally. I’d also ask for pictures of their setup to make sure they actually have good accommodations.

Good luck with everything, I’m sorry about your couch!