A long time ago my trainer told me on a scale of 1 to 10, with 10 being highly excited, if the dog's excitement level is at a 10, it's harder to bring it back down to a lower level than say if the dog was at a low level to begin with.
With my dogs it definately is true. What I did was set up my treats, they knew the treats were on the counter. Repair man came to the house, bark bark, I yell out "yeah cookie time", then all they could think about was the treats on the counter.
Paula, I know its hard to find dogs to help, what about using the parking lot of your training school or a pet store where people bring thier pets, your dog will see other dogs come & go no need for interaction. Thats what someone I know was doing with her dog who became reactive when he was a baby. Unfortunately I saw her about a month ago when I was leaving class. As I approached her she stopped me and warned he was acting up again. So sad to say she still has an issue with his reactiveness. He had played with Lakota when they were both pups, he didn't bark at her but we didn't push it any further.