If you use a cat trap, make sure it's covered in branches so they can't see the trap, they're too smart. Use smelly food.
Then if you catch one, humanely dispatch it, probably with a gun.
You could try a duke trap, I've heard tons of good reviews and have a few myself. Never caught a fox, but that doesn't mean you won't. Might as well give it a try.
Could try fireworks/firecrackers at the den, the smell of gunpowder might chase them off, it works for raccoons here. Throw some firecrackers in a sweetcorn patch and you've got a coon free patch. Gun would work the same, hate for you to waste the bullets though.