[Redwood]

If you have the option you could build her a very large 'catbox', or pick up a very small kiddie wading pool for the same purpose. Small dogs are trainable this way, there's no reason you can't with a big dog too, and teach her to go in it. If you give it a go, I strongly reccomend the sort of cat litter that's basically pine pellets, it'll definitely help on smell and won't track around the way actual cat litter does.