They sell bark deterrents on Amazon and other sites. It emits an unpleasant tone when barking is detected. Put it close to your neighbor's yard. Trigger the barking a couple times while your dog is inside. The devices don't seem to work for all dogs, but I used one ( a fake bird house) for my neighbors large dogs. It worked very quickly. It may be worth a try...
Here's an example product:
https://www.amazon.com/Yunboo-Ultras...%2C171&sr=8-18