I’ve only ever been at 1 barn that did night checks (and I worked there so often I was the one doing the checks). It is not a norm in my area. While it is a nice idea to make sure all is safe, I found that it stirred up otherwise already settled horses. They start to anticipate that a person showing up at night usually brings snacks. Horses start pacing and getting antsy until they get their hay refills. This barn also had the night person pick stalls- so every single horse got disturbed with lights and commotion when it should be a nice easy resting time.
In my opinion, it is a short time between feeding and night check (usually 5pm and 8pm) and then the horses are left alone for another 8-10 hours (time may vary by location). Unless someone is willing to check on them every 2 hours it seems a little pointless to do a night check. Colic and injuries can happen at any time of day, with or without someone there to witness.
My personal horses at home do not get checked on from 6pm to 7am during the week. Most days they only get eyes on them twice a day at those feeding times. On weekends I leave them out in the field overnight so that I can sleep in without worrying that they’ve been locked in a stall for 15 hours. I realize that this is not an option when you board.
In your case, OP, you may be able to talk to the BO to see if night check is an option. If they are not willing, is there internet at the barn? If so, I do like the idea of cameras. Maybe see if she would be willing to let you put up a camera in your horses stall so that you can check on him any time from your phone. But most importantly, just have the conversation to let her know your concerns with the near colic situation and see if the two of you can come up with a solution.