Never had a problem with those items being stolen. Not to say that it could'nt happen. It would take a real lowlife camper to steal one out of a campground, though that too could happen. I try to introduce myself to our neighbors in the campground and keep an eye on things when they leave and hopefully they'll do the same for me.
I keep our camper in the back yard with a fence around the yard. But like several have said, if someone's going to steal something, no amount of locks or cables is going to stop them. I just try to make it as difficult as possible for them and maybe they will move on to an easier target.