Need help with foster Bentley

I have had Bent for about two weeks now I guess (have to check when I posted that I got him, lol). He has come a long way in a short amnt of time! Background for those not familiar...surrendered to ARF by family w/ five children. When brought in he was so scared that owners had to hold him down for vax. He bit when people attempted to touch him in his kennel and would avoid you at all costs. He was most certainly abused to some extent, was petrified of the man that brought him in. He urinates when he meets someone new still but will at least approach people willingly and without growling. He hates to be outside by himself and he hates when I take him to the shelter while I volunteer. He 'kneads, nurses', and cries while chewing/sucking on a pillow.

The problem I am having is when he has been separated from me for any length of time be it outside alone for a minute or after being in the kennel at the shelter he attacks my legs/butt and hands while barking/growling at me. I am trying not to use any form of physical redirection during this time as my hands are really beat up from him already. He is not able to be redirected into a command (he knows sit/down pretty well) and using a loud uhuhuh sound does not phase him from this biting/growling.

Since he is usually on leash when he comes out of the kennel at the shelter I usually hold the leash out and away where he can't reach me while saying NO! but it just escalates him. After a few minutes of him biting/growling he will finally get distracted by a leaf or something else and will settle into a normal walk.

Give me some tools here so he can be put up for adoption, as is I don't feel comfortable telling shelter manager that he is ready.

Have you ever used Tellington Touch? You can find information online, or buy the book by Linda Tellington-Jones. It is an easy massage type of protocol, taking advantage of trigger points, etc. For instance, long side strokes (from the dog's neck or shoulder down to his haunches) will calm an excited dog. Once you have him calm enough, you can use other techniques, such as ear rubs. I've used these techniques and they work on all species (though fish are more difficult ).

Also, use calming signals yourself if you aren't already. Don't talk to him, don't look at him. Act as though you don't know he's there. This type of protocol was minimally discussed in the "how you know your dog respects you" thread. It is used when you have a dog who is very reactive when you get home, but is also useful with a dog who is generally out of control. You will have to continue ignoring him a full five minutes after he settles (use your own criteria for "improvement"). Why this works could be because you are demonstrating that you are the alpha; but it could also be because you are not giving out excess energy; or because the dog reads you as being calm and he is, therefore, safe.

If you are taking him for a walk, use a long line and follow the same protocol of ignoring him and walking with purpose. Change direction every couple of minutes. This may work because you are acting like an alpha; it may work because your confidence makes him feel more secure; it may help because he can use up his energy in a calm yet mildly directed way; it may work because he is exercising while you are using calming signals (basically ignoring him). Time for someone to write a dissertation, but you just worry about Brent.