When I first started metal detecting, in parks and in the city, I was very shy about it, but you get over it. But night detecting? I would think you would be hassled by the police all the time, people reporting prowlers around the school, and any older guy hanging out around tot boxes would have some explaining to do. I think in the states, and especially California, most people, and even kids have seen metal detectors at work, so they shouldnt be a problem, getting in your way. It may be quite and pieceful at night, but when I have my earphones on, I only concentrate on what im doing, and try not to pay much attention what is happening around me. I doubt that a daylight dector has to worry about someone attacking him, in parks or most other places.
Its different here in Thailand, I have people watching me all the time, and sometimes they get so close, that they almost fall in the hole im digging. I have to tell them at least a dozen times a day, how much the detector cost, where I got it and what do I find. One even thought I was looking for crabs! I try to follow the tides, so night or day I detect, but night is dangerous, so I just detect where the beach is lit up, or better yet, with a friend. I have enought stuff to carry, so no guns or other war machinery, just my detector and digger, which would put a nice dent in someone.
I will stick with the day light hours