I have a hitch lock that can't be defeated by a pair of bolt-cutters. It's a solid chunk of metal that fits over the socket, and locks with a key.
And, as has been mentioned, it's a very low probability that you would have your whole rig stolen from a campground. Especially if you are usually there in the evening, and only venture out during the day, and there are other campers around.
Not so for your other gear. I was in an National Park campground in Arizona, and I heard that a few weeks earlier, someone had come through the place at around three a.m. with bolt-cutters and stole several generators. This is why I now have a cheap (forty bucks) motion detector alarm that I aim at my two generators if I leave them out over night, even if I have a good place to chain them up to. It won't go off from small animals and such, but a coyote-sized, maybe even raccoon-sized is suppose to set it off.
I've had my battery stolen from my hitch while I was sleeping inside my TT, WHILE my two brand-new Yamaha generators were running outside. The guy knew I would wake if the ac quit.
Because of this last incident, I've been too paranoid to 'boondock', which means camping anyplace without any hookups or support. I would be freaking out if I left my baby sitting all alone in the middle of nowhere. My precautions might prevent the casual thief from driving off with it, but breaking in the unit would be possible.
So, I pay the exorbitant campground fees for security. Full hook-ups are nice, but cost as much as a motel room twenty years ago. Even a dry National or State park campground is ridiculous; 25 bucks or more a night for a picnic table and a pit toilet somewhere in the campground, possibly no dump station or showers. At least we qualify for the senior 50% off discount.