You have my sympathy, had a similar situation years ago.
With the dog owner being LE that does make it tricky. Are there other neighbors that you could talk to...is it bothering them? Powers in numbers. Where I live a person can make a noise complaint anonymously and if other neighbors are none to pleased with the barking perhaps more than you could file complaints if anonymous is allowed.
Not sure on the neighbors. My guess is that they’re none too happy, but none have ever spoken to me about it. Gut instinct is that they won’t want to rock the boat. And, they don’t have anonymous complaints in this particular town. Damn.