This is just a suggestion that may or may not interest you. What if you got a special box for them to potty on? I use a container called UGODOG for my dog. It is a large container where the pee will collect and on top of the container are two grids with small square holes where the pee goes down into the container and the poo stays on the top for easy removable. You can use newspapers or whatever inside the container if you choose. The name of the company is :
www.ugodog.com if you might be interested in checking them out. It may be the solution you are looking for to keep them confined to one place to go potty and not your rugs.