Honestly, I have heard of very little theft in campgrounds. If you use a little common sense and not give someone and easy opportunity then I think you should be OK.
As a sidebar all RV's have two locks for a reason. One of the locks has a universal key. Meaning a large seller can have one key and still show a bunch of RV's to a buyer. The second lock is unique. I can't remember which is which. I just lock both when we're gone in an unknown campground.
True story. MH I owned the PO mounted a gun safe to the floor of the bedroom closet. I was in a park and the bedroom carpet was wet. Only place it could be coming from was under the safe. As I looked closer I noticed a thumb hole in the floor. Turned out to be a removable floor, and the water pump was hid under it. Sometimes thinking you're secure is 99% of the battle. :)