Glad to hear it. My real name isn't Louie, but I run into a lot of dogs with my real name, so this is preferable.
And the treat thing should work with time. It's what the trainers where I volunteer recommend and do with dogs who are fearful of certain types of people. You could buy some tripe, cook it up, and keep it in your sister's freezer. It's healthy for dogs and something they really like but aren't eating as part of their diet or normally getting as a treat or found scraps. Just defrost a few bites when you come over and it's this magical amazing thing that only appears when the beard guy comes around. I've heard you can get raw green tripe which is even tastier for dogs at pet stores but I've never bought or used it myself.
As a tall guy in a shelter environment there are a lot of small, fearful dogs who come in and want nothing to do with me, but will warm up pretty quickly to women. They almost all become my friends eventually after enough positive interactions. High value food is really good, but even better is fun situations. Sometimes I'll walk up to a kennel and a dog will just growl at me. Later I'll hang out in the off leash area where they get to run around with other small dogs which is a million times more fun and less stressful than their shelter kennel. Often after that they associate me with good things and are much more relaxed. Obviously you won't get a swing that large with a dog who has a safe and happy home, but being part of fun outings to the park might be helpful as well.