^Glad someone said it.
Is he neutered? If not, neutering along with training will help the marking problem. Does he enjoy being in his crate? Has he had a recent vet check lately? There are things like thyroid problems that I believe can cause anxiety issues in dogs.
Really it sounds like all he needs is training. Train him not to chew on things that he isn’t supposed to (reward for chewing the right things, take away and put up the bad things, maybe try bitter apple spray for the things you can’t put up) and train him that his crate is a good place to be.
Have you tried raw bones? Not only are they fun to chew, but there’s also tasty marrow and meat on them. I haven’t tried this yet, but I plan to start getting some nice bones for Dandi to play with this summer.
