How are they on groundhogs? I might need to get one...Forget cats. Find a couple of rat terriers, they will tear the place down to get a rat or mouse. Far, far better than any cat. Unlike cats they also make good companions.
My Rat terriers humiliated many a "good" farm cat in their day. They will go into stack of hay and bring out dead rats and mice. Whatever it takes, they get their nose on it, they will go after it.