We have very commonly used a syringe case with the tip cut off taped on to the tail VERY generously. This seems to work very well, so long as the dog does not chew it off!! The case protects the tail from banging against stuff and is open to allow airflow and to promote healing. Obviously this depends on what stage you're on in the healing process.

SO GLAD to see her tail is healing as well as it is! My sister's dog was one of the kennel dogs while I was in school, and he had a pretty bad case of happy tail, nearly came down to amputation. These can take mooooooonths to properly heal, or longer! I have had to assist in many tip amputation surgeries from tails that just refuse to heal (be it owner compliance or "dog compliance"...). And always always always use an e-collar with these guys so they can't chew on it or chew off any dressing used on the tail!