By reporting to the police, they would likely at least stop him and ask to see inside the rental truck and as he likely had already stolen things, they would have him. They would have probable cause to at least do that. And remember, although bear spray (you can bring it into Canada from the US) is designed for bears, it would work just fine in a pinch for a two legged predator. I would be really worried about someone who would open a door early in the morning of a camper with a vehicle likely close indicating occupancy. If they don't care that someone is in the trailer, that would make me very nervous. Of course since they are Canadian, they would likely be very polite about doing you harm.