Fabulous dogs the CC's. Love irons out a lot of past negativity. Give lots of love and affection, and TRAINING. These are dogs that like to be engaged. They like to have a job. They like responding to expectations (especially if training treats are involved
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One of our old members who is somewhat retired from the Forum used to advocate for Mastiffs (in particular, Mastiffs) to be allowed to sleep in the same room as their owner. The reason was that they are a very emotionally deep dog type. Now, if that sounds extreme, I have to tell you, they are...they are very, very emotional. I had war with my husband about allowing our girl to sleep in the same room, but it worked out for the best, and now it is just fine. (He snores, my girl Mastiff snores and, if my husband can be believed, I snore.)
Sleeping together supports the dog's mental health, and it sounds like your girl has had a few bad breaks in life, she might benefit from the closeness. Separation Anxiety can be a very difficult thing to deal with and sometimes is just means letting them be in your presence, but, it isn't that simple.
I was lucky, I had the summer off when we got Bailey our girl. But, I had to get her used to me going back to work, so, I would get up every morning, bring my housecoat downstairs and I'd place it on the living room floor. I would get a few treats and place them on my housecoat. I would kiss her and tell her I loved her and I would go out the door. At first I would only be gone for 15 minutes, but then 30 and then an hour and then...well, you get the picture. And I did this little ritual for at least a month or more. And, by the end of the summer, my girl was not scared and was not filled with anxiety, she was sad, maybe, but comfortable. Mommy always came home. She'd snuggle up on my housecoat, sniff my Mommy smells and eat her treats. Mommy always came home and life was good.
As for lunging, well, I haven't had that problem, so I'll refer you to Glen and Boxer Girl and the others who have had to work with this problem from scratch. I can tell you what it will look like when your girl is calm and assured...she will stay by your side with only a word from you. Even when a dog fight breaks out at the dog park, a simple word will keep her at my side. She obeys. It's a beautiful thing. However, if I were to say "bad man", she would go on full protection mode and scare the "you know what" out of anyone who planned to do our family harm.
They are a great, soulful breed, worth their considerable weight in gold. Love, Honour and Cherish your girl...She will Love, Honour and Cherish you and your Pack (family) in return.