For what it's worth, you are MUCH more likely to have break ins while the RV is in storage than while on the road using it. Break ins and theft in the campground is not a common thing but in a storage lot it is VERY common.
As for security, Most Rvs are an easy target since they can be broken into with a small hammer or can opener. It's a GOOD thing that RVers look out for each other and that theft among them is rare. I've been camping for over 50 years now and have been in commercial RV Parking lots and back country campgrounds and NEVER had anything stolen.