depending on where you live, (small town or city) the sign may be a violation. I know larger towns have rules about signs. Call city hall if you have one. Good luck.
On a more devious note, I would do things in front of the cameras that would make him call the police. For instance, get a dozen potted plants all alike that look similar to marijuana. Take them out of the house once a day and water them in the back yard. Then, looking all around, bring them back into the house. Leave them in a room in sight of the camera with grow lights on day and night.
or go out at night and dig a hole in the back yard, put a "bundle" of something in there. Cover it up, look suspicious.
After a few false alarms to the cops, HE will look like a kook.