my boys have chewed a hole in the middle of my bed, a hole in the wall, and my couch… i found that toys,bone,cow nuckles did little.
but i did find that a thick canves, (like military tents are made of). wrapped around a rope or tire hung from anything high. tree branch ect…. this gave them a challange and plenty of durabilaty and the chewing stopped. worked for me maybe you too. ps get them interested in the wrap by rubbing with treats.