Cook 6 bacon slices in a large skillet over medium heat until crispy. Transfer the bacon to a paper towel-lined plate and set aside.
Place ½ pound deli turkey on a microwave-safe plate and microwave for 30 seconds until warmed through.
Spread 2 tablespoons butter evenly on one side of all 4 slices sourdough bread.
Heat a large skillet over medium heat. Place 1 slice of bread in the skillet with the buttered side down.
Top the bread with 2 slices provolone cheese, ¼ pound deli turkey, 3 bacon slices, and ½ sliced tomato.
Spread 1 tablespoon mayonnaise on a second slice of bread and place it on top of the sandwich with the mayonnaise side facing down.
Cook until the bread is golden brown on the bottom. Carefully flip and cook until the other side is golden brown and the cheese is melted.
Repeat the process with the remaining 2 slices sourdough bread, 2 slices provolone cheese, ¼ pound deli turkey, 3 bacon slices, ½ sliced tomato, and 1 tablespoon mayonnaise to make the second sandwich.