There are some other options to be had for a non-lethal, early warning system. Tripwire flares, those chem-light trip wire contraptions (best if you have IR devices and use the IR chem-lights, but if your bad guys have IR equipment then they can see it too), and the old group of cans on a string.
If you have an alternate power source, you could have some cameras and stuff positioned in areas, with a live feed coming back to you, just make sure, like all the other stuff, it’s camo’d up real good.
As an aside, this thread is great! Lots of good ideas!
Canadian Patriot. Becoming self-sufficient.