Hi there! What you wrote sounds so familiar to me too. We had a German Shorthair Pointer who died in June at the age of 15 yrs and 4 mos! When he was young chewed up a lot of things including a custom-made dutch door and dry walls almost to the electric code! He also ate 64 color Crayola and a whole box of Andes mint chocolate!!
You know those hunting dogs need a lot of mental and physical exercises. I think your dog is bored when he is alone outside. Throwing balls or Frisbees, or running is good. Find some activities that he can burn out his energy everyday.
Also, taking him to an off-leash park, or a training class for socialization and interaction with other dogs will help.
Please be patient and give him time to grow. Hope this will help
