Good luck with the pup. You mention that she runs and hides. I know alot of the people on the list suggest part of the training is to put a leash on in the house and have her connected to you. I'm just wondering if the lease would be a good idea when she goes to hide. Any thoughts from the list? My other thought was to have another dog around to help her socialize, but I think you have that covered.
I too got a puppy who was not properly socialized as a puppy and has some of the same issues. She was deathly afraid of new people and other dogs. My first suggestion would be finding a relative or someone you are comfortable with that does not live near you to take the puppy for a couple weeks. This will get the puppy away from you and force her to become more independent. Since you live in a small town and have few chances to get her out and see new people/places you may fall into the trap of really sheltering the puppy. The second thing that has worked for us is finding something that the puppy really really really wants more then anything, for us that was a tennis ball. Bringing a tennis ball with us and showing it to her during stressful times allows her to focus on the ball rather then how afraid she is, also letting strangers throw the ball whenever we can. Hang in there and be persistent.