Build a campfire and let it burn down to medium-hot coals, or preheat a camp stove with a skillet.
In a bowl, whisk together soy sauce, brown sugar, ginger, lime juice, salt, and pepper. Add chicken, pineapple, and bell pepper. Toss to coat.
Tear off two 18-inch sheets of heavy-duty aluminum foil. Lightly oil the center of each sheet.
Divide the chicken mixture evenly between the two foil sheets. Fold the foil over to create a packet, crimping the edges tightly to seal.
Place packets directly on hot coals or on a grill grate over medium heat. Cook for 18–20 minutes, flipping once halfway through.
Carefully open one packet—steam will escape. Check that chicken is cooked through (no pink inside). Let rest 2 minutes, then serve directly from the foil.