it really sounds like he needs to be rehomed with someone who has the space and time to spend with him. my DH had working dogs that he ended up having to have at home when he finished working away. i found it to be cruel to them to not have enough room to let of steam, and not enough stimulation. they were getting snappy so we talked about rehoming them. DH would take them to friends farms regularly, but it wasn't enough. one passed away naturally, and after investigating, we found the other had some issues with his health that were going to make him much more ill and in pain over a short period of time, so we had him put to sleep. he was getting VERY nasty (bark wise) and i wasn't at all comfy having him near DD, so we talked about it for a few weeks and decided that was in his best interests and the most humane option. i would never have forgiven myself if he had hurt DD in any way...