OK, I have to chime in here (no groans please).
I have never been to a campground (even ones where I looked around and said to self - "Self, last time here!), that I felt in any way that the CAMPERS were going to steal something from me. I have had sites along a road, along the beach where folks blasted by during the day on wave runners, and parked in my driveway where I was concerned with "casual theft." I ALWAYS say hello to my neighbors so they see my, and my wife's, face and know who is camping there.
No matter what you do, you can not secure your valuables at a campground. We all know that and hopefully "town watch" our campsites, not matter how short our stay.
Valuables very difficult to secure without modifications include:
Every storage compartment. Check your keys. CH-751 right?
Your lawn chairs, tables, outside lights, etc
30 pound bottles of propane - full they are worth almost 100 bucks each and BY LAW can not be in a locked compartment.
Power Cord, yes - but most of us have 30 amp extension cords. How do you plan on securing those?
If you have an autoformer on your power line (400-500 bucks) a bike lock can be removed in seconds.
Bikes (300 - 1000 a pop)
Your grill - 100 to 500 bucks
Your spare tire(s)
My point, and I think Windrider was trying to make it too, is that since security in a campground is impossible, the only way RVing works is to have few (no) thieves and lots of caring folks that watch out for others stuff as if it was their own. You can not stay at the campsite all the time.
We had set up at a campground and blasted off for a local museum before it closed. We had never seen our neighbors. Grill, chairs and bikes were outside like normal. When we got back about 3 hours later the roads were wet and I said, wow our stuff is going to be soaked! I was wrong.
As we approached our site I saw our stuff was MISSING!
Panicked a bit, till I got closer. Everything was either under the camper or covered with large garbage bags. The neighbors we never saw protected our gear when a sudden shower came up. We met them later with a wine bottle in hand.
We go camping to enjoy the outdoors. You are not camping in South Philadelphia. Take appropriate security measures (knowing where the thunderstorm shelter is comes immediately to mind as a security measure) like changing your storage door locks, but don't let worry about losing your gear make you paranoid. RVing will be "No Fun" if you do that.
Remember we do this to: