Mike runs a 200-acre corn and soybean farm outside Springfield, Ohio. Like most farmers, he leaves his equipment in the field during planting and harvest season. Tractors, planters, grain carts — they're too big to put in a barn every night. Last October, someone walked onto his property at 2 AM and stole the GPS guidance screen from his tractor. $8,000. Gone. The tractor was parked 300 feet from his house. "The worst part wasn't even the money," Mike told me. "It was knowing someone was on my land while my family was sleeping." That's when...