So along with locks, specialized insurance coverage and locking racks. I also use bicycle alarms. They are really loud and attract a lot of attention when someone tries to move our bikes. Plus they are out taillights. My understanding is headlights and taillights are required at night.
https://www.amazon.com/gp/aw/d/B071...bike+alarm&dpPl=1&dpID=51c+kYZ5fgL&ref=plSrch
https://www.amazon.com/gp/aw/d/B071...bike+alarm&dpPl=1&dpID=51c+kYZ5fgL&ref=plSrch