There’s been some discussion about this on another thread on this forum – I think it was the one about gas alarms.
I’ve had the same problem as you, Joe, my tent cleaned out while I was in away in town. I put in the extension to my leveler control from Dactyltech, but I know it comes as a standalone box as well. The problem for me was twofold. First to detect intruders without lots of useless false alarms, second was getting notification on my cellphone.
There’s 3 types of detectors I thought of using, each with some pros as well as cons. A PIR will only work in a tent that flaps or shakes in the wind if you mount it looking downwards at the floor from the ridgepole. If it looks at the tent walls you get false alarms every time the wind blows. But mounting it on the ridge pole means you need to cable it back to the control unit, which is a bit of a hassle. A PIR can cover quite a big area in you tent and won’t false alarm unless it starts swinging.
Other than that I wanted to put a pressure sensitive mat under a rubber sheet near anything that might want to get stolen, but right now there’s no stock in the country of the right stuff for the job. I hear there is stock on the way though. A pressure mat is pretty resistant to false alarms, but it is always smaller than you want it to be. And quite expensive by the look of things.
I also have a sonic, or ultrasonic, scanner on the outside wall of my caravan and a plastic curtain like they use with shower stalls to bounce the sound pulse back to the scanner. Anybody walks between the two, or moves the curtain, it sets the thing off. A bit more prone to false alarms, especially if you make the gap to the curtain more than 2 metres. Also it needs a quite sophisticated control unit to time the sound pulses and measure the echoes from the curtain.
The important part of the whole setup is the control unit, which can send text SMS messages to my phone as long as I’m in range of a cellphone tower. My box also comes with a couple of LPG detectors, and water meters which you may not need or want, and four more alarm zone inputs for magnetic door switches etc. I think the standalone has all this stuff also, and it’ll be a lot cheaper.
I hope this helps you. Check out the other thread, I think there might be a link to their website there also.
Cheers and good luck.