Combine first 9 ingredients in large zip-top plastic bag. Add pork, turning to coat. Seal and let stand at room temperature 30 minutes.
Preheat oven to 425°. Heat a large oven-proof pan over medium-high heat. Add pork; cook 2 minutes or until browned. Turn pork over, and place pan in oven. Bake 15 minutes or until desired degree of doneness. Remove pork from pan; let stand 10 minutes. Cut into 1/4-inch-thick slices.
Spread mustards evenly over cut sides of bread. Top bottom half of bread with deli ham, pickles, cheese, and sliced pork. Top with top half of bread. Cut loaf crosswise into 4 sandwiches.
Heat a large skillet over medium heat. Lightly coat sandwiches with cooking spray. Add 2 sandwiches to skillet; place a second heavy skillet on top of sandwiches, pressing gently. Cook 3 minutes on each side or until cheese is melted and bread is golden brown. Remove sandwiches from pan; repeat with remaining sandwiches.