Need urgent help with a weird situation – any advice?

I’ve run into a bit of a situation here involving some local thieves! So, my father runs a small roadside stand where he sells all sorts of homegrown goods—fresh fruits and vegetables, olive oils, dried figs, homemade jams, you name it. The thing is, because we’re located right off a main highway, we’ve become an easy target, and it feels like we get broken into constantly. They’ve already made off with several hundred dollars worth of produce, and honestly, it’s getting frustrating. Since we don't have any electricity running at the stand, I'm trying to figure out how to secure the place. Should I look into a battery-powered alarm system, maybe a high-end camera with excellent night vision, or perhaps a motion sensor that sends an alert straight to my phone via SMS? I really need to find a solution quickly...
Here are a few more specifics: 1.2 miles We are situated just off the house near a public thoroughfare, and these guys always seem to strike under the cover of darkness. It’s getting so bad that I’ve half-joked about setting up a tripwire mine, though at this point, I’m not even sure if I’m joking anymore. Anyway, does anyone have any advice or recommendations?🙏

If you don't have power, you're stuck relying on a battery... try picking up an old car alarm system and rigging it up. You could use microswitches on the doors and windows... or just set it off with an ultrasonic sensor...

Alternatively, just grab the loudest 12V piezo siren you can find at an AutoZone... wire it up with a latching relay (once it gets a signal, it stays on until the battery dies) and connect a microswitch to the doors or windows. Once it trips, that thing will scream until dawn... when you're closing the doors, just wedge a piece of cardboard or some tape to keep the switch from triggering... you could even mount some car headlights and wire them to the high beams... just make sure you mount everything—the relay, the siren, the battery—in a spot that's as high and out of reach as possible...

thank you so much