Habe you thought about socialising him with other dogs? My besteht friend has a dog with similar temperament like yours. She went to a 'toddlers group' with it right after she got the dog. There was no exercises, it was just people and their puppies meeting outside in the green where the dogs had time to ply with another. She found that through a note at the Vet's info board.

Do you know the tag 'dogsofsteemit'? A lot of photoshonly posts but some interesting reads and the best post get showcased.