If it's safer during the day, it's always easier, because you don't need your flashlight unless you are in a dark spot, or want to check a crevice, or give your photo some better lighting, rather than at night, when you need it ALL THE TIME. Plus you don't have to worry so much about accidentally shining it on a window during the day.
In my experience, bums don't generally want to mug you, and if they harass you, just give them a few bucks and they'll go away. It's scrappers you want to worry about. In some places, they'll actually try to do you severe harm cuz they think you're trying to hone in on their scrapping biz. Scary stuff.