Dogs do have a need to chew and I think they should be given specific things to chew on. I have use bully sticks and even real bison back rib bones with my dogs. You might want to ask your vet what he recommends. Also, you might want to consider washable pee pads, they are less likely to chew on those. Petsmart sells some great ones.
Top Paw Washable Training Pad | Potty Training | PetSmart. I've literally washed them thousands of times and seriously no signs of wear. They are thin but hold an incredible amount of urine, my son's 20 lb Shih Tzu, used one when he was visiting and no leakage.
I do think part of the problem might be separation anxiety and perhaps this article can be helpful.
Chewing - Why do dogs chew? Stop your Puppy Chewing | Vetwest Animal Hospitals