Is the TM secure?

We are seriously considering buying a 2002 TM 3023 previously owned. I am so happy that I stumbled across this website!! It has answered nearly every question I could possibly have. We had researched TM's a while back, but the new ones were way out of our price range, and again, as luck would have it, we stumbled across this used one. It seems to be in good condition. I did have one question though. This one does not have a deadbolt on the door. We intend to install one. I read all about the door problems that people have had while driving, but what about while you are camping? If you go to a campground, (for example, the campground on the beach in San Diego) and want to go exploring, would the door locks do the job to keep most would-be thieves at bay? I know that if someone wanted in bad enough, there probably isn't anything you can do, but it would be nice to hear from some of you who own them if you feel comfortable leaving your TM locked up at a campground. Again, I feel so fortunate to have found this website. It has been a wealth of information, and has really helped us decide that this is the travel trailer for us. We are upgrading from a 97 Coleman Niagra Tent Trailer.