We had problems spread over many acres up front we bale, where they would mound up dirt with rocks that were great at dulling the blades cutting the hay.
The one at a time methods were not even a consideration, I made this device.
For years my father has been killing gophers with a modified pry bar and cups of poison, baiting tunnels a few hours at a time as he felt like it. We just finished a machine that baited the problem spots over 32 acres in under two hours. I had the 3 point hook up leftover from another project...
www.tractorbynet.com
It creates a tunnel under ground and drops a few poison covered seeds into the tunnel every 3ft. Drop it down around active areas (where you see mounds) then raise it and go to the next spot.