p.s. - No crate soiling. Also, if I repeatedly lock up, walk to my car and back while he isn't crated, he just looks out the window and waits for me without any whining. I wonder if he'd do better without a crate at all, but I don't want to chance him jumping through a glass window or anything. I sure wish I had someone he could stay with while I was at work. =(

Do you have any doggie day care in your area, or any kennels that would let him stay there during the day?
Did he live with a foster parent before you adopted him or was he kept in a kennel? Would you be able to set up access to a large, outdoor kennel from a small room in your home ?

He's calm while watching you walk to the car because he can still see you. I would worry about destruction to your home if you left him uncrated all day and I think it's going to take time (maturity) and training before you can leave him unsupervised all day. I say this because DS once owned a pit mix and as a youngster she was destructive when bored.

Yeah, I had a friend who found a pit as a puppy and he would chew on the drywall when alone lol. I really wish he could spend the first couple of weeks at a doggie day care, but I work at night. My closest relative lives about an hour away, so it would be four hours of driving every day to leave him with her. He was in a kennel at animal services before I adopted him, and as soon as I walked away (he needed to be neutered before coming home), he began crying.

The one thing you have to teach him is that you are coming back. With ours, who btw ate a few couches and a banister, we left the house,(where we couldn't be watched) for about 3 minutes.
When we left we used the catch phrase " be a good girl!" and left. First time or two it was 3 minutes, spent the entire week end working up to 20 minutes. Each time we left we used the same phrase. "Be a good girl". She learned that we were going away for a bit but we were coming back.
Then we went for longer periods of time until the separation issue was non-existant.

Even to this day, 9 years later we used the same phrase. Now she turns her back on us and goes to her bed by the couch. Until we are gone and then it's ON the couch. We are smart humans, we know the couch is warm the bed is cold when we get home.

Luckily, I have the weekend off, so I'll be able to do some more work with him!

OMG, I went through this with my little Tubby and I know how you feel. Mine was in a shelter, in a damaged cage next to his sibling. Both were deposited at the same time. When I brought the little fellow home, I was not prepared for what happened. He would not let me out of his sight for an instant. I had to put him in the car, drive back to town and get him a crate so I could bring him up to work because he mutilated himself if I was out of sight. He only stopped crying long enough to chew his tail to the bleeding point. My husband was out of state and thankfully I owned my business and it was on my property, so up to the greenhouses he would come with me. It continued, I could not go from one structure to the other without him chewing at the metal bars to the point of injury.

I did just exactly as Justplaincountry said she did. He had to learn that when I was out of sight, I would return. I told him to be a 'good boy' and did the come and go routine for days, extending the time by a minute or two. Then when hubby came back he was tolerating ten or twenty minutes and we took turns being inside with him or taking him on leash to 'visit' the other. Even a month or two later we were afraid of his anxiety level if we went for more than an hour or two, so we dropped him off at our daughter' house nearby to socialise with her pooches. We used to do the same for her dogs. The moment of truth came later that summer when my cousin died and we went to her services. It was four hours and that didn't even include staying for the wake. When we got home, he was fine and has been ever since. They just need to know you'll be back. I suppose this has something to do with trusting another human who never did come back. God only knows what they went through in a previous life. I believe mine was treated well. He came trained, healthy and with manners. Somebody broke his heart.

You've gotten some really good advise and teaching techniques. One thing I was told to help correct or avoid that problem is to not engage in big hellos or good byes. Just come and go with a greeting and quick pat and leave it at that. The less of a big deal you make it the less they will stress out about it.

Sep anxiety is so painful - for dog and person!
I just ordered these books, and am hopeful of preventing as I just brought a "rescue" from the shelter home.
I know from experience that it takes a lot of work, a ton of patience. If you can find a good behaviorist it's worth it. Email Jean Donaldson for a referral - I just did yesterday and got an immediate answer for two reliable trainers in my area.
jean at academyfordogtrainers dot com

The books:
"Don't Leave Me! Step-by-Step Help for Your Dog's Separation Anxiety"
Nicole Wilde; Paperback; $19.95
This book comes recommended by Karen Pryor. She has a shorter one on same topic.

AND:

I can't wait to read this one:
"Do Over Dogs: Give Your Dog a Second Chance for a First Class Life (Dogwise Training Manual)"
Pat Miller; Paperback; $12.21
In Stock
Sold by: Amazon.com

Here is a link that might be useful: Try here, too, for referrals / advice