If you have concerns about your safety, my basic advice is to reconsidered the your choices of RV parks. As others have said, safety problems are RV parks are rare, at least outside of major metro areas. Perhaps if you could be more specific about the concerns you have, we could offer more specific advice.
Petty theft can be a minor problem in parks that are in or adjacent to cities, where others may wander into the park, bent on mischief. We don't leave much stuff outside if we have to stay in places like that (we usually look for more rural parks). In 20+ years the only theft losses I can recall are some beverages from a cooler and a couple of our potted plants. We've stayed in a few places that were rowdy or the denizens (usually long term residents) would get into arguments with each other, but no had any threats to our own safety. We did keep an eye out, though, and moved on quickly. If you aren't comfortable in a park, GET OUT! It's one of the advantages of RVing - you can move easily if you don't like the surroundings.
If I thought I needed an alarm system or perimeter cameras to be able to stay in RV parks, I would quit RVing.