Where it can be done, mark two parallel lines and move golf balls from the near to the far line. Scoring can be by time or round count. All the usual safety and clean-up considerations apply.
Cut small logs into chunks with length roughly equal to diameter, make them more visible with water soluble poster paint or flour slurry, scatter them around a small valley. When you walk the rim and slopes of the valley you get shots of random range and elevation, great practice for hunting. When your cleanup efforts miss some targets, the targets will eventually rot away.
Gee, I'd love to see your data!