I asked the same question about a year ago. I got a variety of responses, some no doubt will repeat here. For me, it's a matter of where we are camped. I have a 50 foot wire also. So far, it's never been tampered with. I carry a bicycle cable with pad lock and wrap it through the handle whenever I can secure it to something. But that is not always possible. I know, anyone can snap the cable with a bolt cutter, but at least it will keep honest people honest.
I had problems getting a signal when the Tailgater was set too close to the camper. Maybe the metal in the camper affected the signal somehow? I don't know. But it quit doing that. So, whenever possible, I now bicycle cable it around the trailer tongue jack. I'm going to experiment with putting it on the roof, but still leery a heavy wind could blow it off.
Another option is to drive a stake in the ground and bicycle cable it to that. At least it will take an extra second and will keep a "snatch and run" from happening by some kids or something.
Really, there is no good answer, I've not found a good solution myself. It still is a matter of trusting your fellow campers. But... times are changing too! (unfortunately).... :(
