I watch the local video recordings of thefts posted online.
Like car thefts, there are different levels:
joy riding - these are the opportunists. They are just looking to get what is inside the RV and easy to carry away. If they see there is no security like a hitch lock, they may decide to just take the trailer, but they weren't planning on it. Basic locks, etc will deter them.
auto theft - these are the ones that you want to be able to stop. They see an unattended trailer with no security and easily accessible. Just pull up, attach the chains, and get out of there. They can stop and hitch correctly once they get out of visual sight. They will sell the rv to the homeless or addicts for a few bucks after taking everything out of it. It's a quickie job for some quickie money done by people who survive by theft. They have tools to break through the basic security (bolt cutters, crowbars, etc). They have scanned the area and know when to hit. They fake stories for the neighbors if questioned. And they will leave and come back later to finish the job. They don't care if they destroy your rig in the act. This is where the multiple lines of defense is important. Each defense must be enough to slow them down significantly from getting the rv moved (a hitch lock won't slow them down because they'll just hook up using chains). No one thing will stop them. You need to make getting the rv a major hassle.
chop shop - these are the bigtime thieves. They will bust through all your security to get your rig. They want YOUR rig for a reason. You're not going to prevent these guys because they have the tools, resources, and incentive to succeed. They will break through the highest levels of security to get your rig.
Probably about 75-80% of crimes with rvs fall into the joy riding category. Maybe 9-20% fall into the auto theft category. Only 1-5% will fall into the chop shop category.