Hi Hoover.
I just wanted to send you a hug really for being such a nice animal person to continue working with a dog with those kind of Issues in your life. It must be very stressful at times.
I did look after a dog with severe aggression issues towards people. She was not my dog- I had her for 3 months and did a lot of work with her massive insecurities, helping her to walk out more confidently, not be scared of everything she saw, taught her recall, tricks and how to play. She was such a brilliant and intelligent dog, but had such a deep set fear of people that with her new found confidence, she went from fearful aggressive to pro active aggressive and started protecting me and attacking anyone who came in the house-not a great outcome but what I did notice was that she didn't do it if there was another dog there.
I'm just wondering if you have more than one dog or if your dog is an only child. This one I looked after would behave very differently if there were other dogs with her. I think she was an underdog. Scary though she was, I think it was born out of a lack of confidence and not knowing what alternative behaviour to do. If there were other dogs there, she would let them decide what happened. The minute they left the room it was like she was thinking oh no- now I'm in charge I don't know what to do. If in doubt, attack!
I realise (assuming you only have the one dog) that just producing another one is not particularly practical but I wonder if you found yourself in a similar situation again if plunking a well balanced dog in the area with her would make any difference. Might be interesting to see if another dog has any affect on his behaviour anyway.
I think in case of emergency I would get myself one of those rspca noose sticks just so you can grab him if you need to.
I really feel for you. You love the dog but it's stress. Been there.
I probably haven't been been any help but I do wish you all the best.