If it was a silent alarm I'd go for it.
I suspect neighbor campers would be frowning on a loud ALARM System going off at the camp ground especially in the middle of the night...
Much like when you hear someone accidentally set off their truck horn in the middle of the afternoon. Do you go investigate? I don't...
The only thing I have at my camp site if a motion detector setup that turns on my awning light when someone walks up... I suppose I could rig up something to send out a transmitted alarm using something like the C CRANE FM Transmitter module. If I hear tones going off in my portable FM radio I know it has been activated. Of course the range of this FM Transmitter is not very large.
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Trail cameras might get you a good snap shot of an intruder to show the local police I reckon...
At my camp sites I work hard to keep things out of sight - out of mind when leaving the camp site unattended... Anything of any importance is always kept locked in the truck out of sight. That includes my 2KW Generator...
Roy Ken