Heat oven to 425ºF. Prick each potato 3 times with a fork and place each on a piece of aluminum foil. Evenly drizzle 2 tablespoons olive oil and 1 teaspoon kosher salt over all potatoes. Wrap foil around each potato and place directly on oven rack; bake 1 hour or until fork tender.
Heat remaining 2 tablespoons olive oil in skillet over medium-high. Sauté chopped sausage in oil until heated through.
Remove potatoes from foil and cut an 'x' on top of each one. Squish the ends toward each other to open the potato. Sprinkle 1 tablespoon Mexican cheese over each potato; top each with 1/4 of the heated sausage. If desired, serve topped with sour cream, green onions and cilantro.