Lightly spoon the flour into dry measuring cups, and level with a knife. Combine the flour, baking soda, and salt, stirring with a whisk to combine.
Place granulated sugar and butter in a large bowl; beat with a mixer at medium speed until well blended (about 1 minute). Add the eggs, 1 at a time, beating well after each addition. Add banana, yogurt, rum, and vanilla; beat until blended. Add flour mixture; beat at low speed just until moist. Stir in 1/2 cup coconut. Spoon batter into a 9 x 5-inch loaf pan coated with cooking spray; sprinkle with 1 tablespoon coconut. Bake at 350° for 1 hour or until a wooden pick inserted in center comes out clean. Cool 10 minutes in pan on a wire rack; remove from pan. Combine powdered sugar and juice, stirring with a whisk; drizzle over warm bread. Cool bread completely on wire rack.