Large-acreage ranches
Cattle and game ranches spanning 500+ acres are too big for cameras and too remote for hardwired alarms. Game cameras catch one frame; you need to know who is coming and going across the whole property.
Place units at choke points - gates, water sources, equipment yards, line shacks - and let them passively monitor for active devices in range. Solar power and LTE backhaul mean no infrastructure is required.
4-8 units for a 500-acre property; more if perimeter coverage matters