How do I find out what size gong I'm allowed to hire a worker to use, in the middle of the night? I mean, I know it says whatever size the select board or alderman prescribe in writing, but does anyone have a ballpark size here?

All joking aside, sorry you are having neighbor problems, it's something that gets easier with practice. If you are buddies with any of your other neighbors, you could ask their advice first too, they might have the skinny on what's going on.