lanes in the Great Lakes are well known and followed. There is big ship traffic that does not follow the lanes, such as those that run between Canada
Stay out of the shipping
lanes- that simple really. Particularly where the ships are coming out of restrictive areas, such as inter-lake lock systems.
I don't know that AIS could save you. I've been near the west end of Lake Ontario
at night and seen five freighters bearing roughly my location and I given their close proximity I don't know that they'd have the ability to avoid you and each other.
It's quite common that I sail just offshore
at night, so no threat from freighters there. But the real threat is sport boats doing 45mph headed home from a bar after a good day & night of partying. I don't know anyone that's actually been hit by a freighter, but I do know people who have been hit by powerboats with drunk drivers.
I consider the greatest possible threat to be any one of the weird things I've seen happen to others- shaft backs out and boat fills, part of the hull
suddenly departs sinking the boat in seconds, underwater obstructions, etc.
When crossing lakes, at night, and early/late season I keep a "to go" drybag ready at hand in case we have to bail without time to broadcast a Mayday.
With a baby, I'd suggest one of those self-righting baby baskets- a baby even in mid-Summer water
won't last an hour. When my sailing buddy was a baby I played it safe and stayed near shore, sailed only during the day, and only short hops.