I took Earl down by climbing onto the horizontal refrigerator then up onto the roof. Take a Defiler or a couple of Spiked Bats with you, plus two pizzas. When you defeat him, he drops a sniper rifle. Though I don't advise its use against the others - they're a much better shot.
Also, it's really, really satisfying to beat a dumb redneck down with a bat with nails in.