The STRIDE ST6 Lite is a small, light 640 thermal monocular you can carry in your hand or run on a helmet. The true 1x base view lets you walk and scan at the same time, which is exactly what you want checking pastures or tracking hogs at night. It runs on a standard 18650, so a spare rides in your pocket.
Product photo: RIX Optics. Specs per the manufacturer; call to confirm the exact model in stock.