A bored dog is a dog looking for trouble. Chew toys, ie, kong toys are great. Stuff a tiny amount of kibble in the kong, and watch him go to town. I would also play with him---toss a small tennis ball/toy for him to retrieve. You can also freeze kibble in a kong and give it to him. I give it to my dogs in their crates, so the broth doesn't get on the rug.
Can you get some 'bitter apple' from the pet store? it will usually stop dogs from chewing stuff. I used it to coat telephone wires etc.