1. Place bacon on a microwave-safe rack in a baking dish; cover with paper towels. Microwave at HIGH 7 to 8 minutes or until bacon is crisp. Drain bacon, and set aside.
2. Spread mayonnaise on toast; layer avocado, bacon, onion, and next 4 ingredients each on 4 slices bread. Sprinkle with salt and pepper. Top with remaining bread slices. Garnish with sweet pickles, if desired. Serve immediately.