Yeesh, that's a worrisome problem, especially if you have lead based paint anywhere!
My first GSD, Purdue, cut his teeth on the leg of our solid walnut dining room table. I thought my Mom was going to have a conniption fit! The table is now an heirloom with a fond memory of our wonderful Poozy, and we wouldn't sand the toothmarks out for anything - even if they weren't too deep! (lol) By the way, I have the table now - he was my dog, after all. (g)
You might try the bitter apple spray, or even rubbing a fresh, split jalapeno over her favorite chews if the bitter apple doesn't work. The jalapeno should be hot enough to be unpleasant for awhile, but not hot enough to blister. Just don't use anything stronger! And do try the bitter apple first. Test it out on a part of the wood that doesn't show first to make sure that it won't discolor it.
If she won't quit, your may have to put her in a room where there isn't much for her to chew on while you're gone. The bathroom might be one to look at; just make sure your towels and things are up out of her reach! She'll probably outgrow it after awhile. I won't even suggest leaving her toys because I know you do that already, although a loaded treat ball might help if she doesn't have one.