Have you tried bitter apple/cherry? You can get it at any pet store and it tastes terrible to most dogs. It's odorless and doesn't stain, so you could spray just about anything he regularly goes for.
Also, I second what Chels said: crate him when you can't watch him like a hawk.
Bitter apple is amazing to me, which I can pull my puppy away from a cable give it a bone, distract it, do many things, but if I take my eye off for a second she's back on the cable. If I spray bittle apple, she'll smell it, maybe take a lick/bite and run away. When it drys out it doesn't work so well or you have to reapply it often.
I don't think bitter apple is the best thing for it, it's probably better to distract it and give it a bone or something you want it to chew on. Spraying the item helps so the dog won't keep going back to it.
The ingredients are mostly alcohol and I've heard you can mix lemon juice and a dog won't touch it. But I've read that some dogs actually like bitter apple. My puppy runs in a hurry.