Any ideas for keeping bears out?

I also think its a human. Shooting a bear out of season is illegal and will cost you big time, loss of firearms and a fine. Contacting the police and the wildlife management office is sound advice. Do both. Make a report. If it is a bear it could be desensitized to humans and potentially dangerous. Wildlife management would be interested in it. Also, booby traps like electrifying something could be against the law too. If that should kill someone, no matter them trying to break into your trailer, you are screwed. If an electrified type of thing is used it must be posted as such. Hope you have a good defense lawyer on speed dial. Get one of those motion activated cameras hunters use and locate it where it cant be reached easily and see what it shows.