Cook the bacon in a medium skillet over medium heat until crisp, about 8 minutes.
Transfer the bacon to a paper towel–lined plate. Transfer 1 tablespoon of the drippings to a small bowl.
Add the oil, vinegar, and ¼ teaspoon each salt and pepper to the bacon drippings. Whisk and set aside.
Shred the chicken meat, using your fingers or a fork, and discard the skin and bones.
Combine the lettuce, cheese, tomatoes, avocado, onion, and chicken in a large bowl. Crumble the bacon over the salad and serve with the vinaigrette.