Place the bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Remove bacon to a plate lined with a paper towel, retaining drippings in the skillet.
Break ground beef in pieces and add to drippings in the skillet. Cook and stir beef until completely browned, 7 to 10 minutes; drain in a colander. Rinse beef with water to wash away excess fat; drain. Transfer drained beef to a bowl. Stir pickle juice into the beef; season with salt and pepper.
Combine ground beef mixture, American cheese, cream cheese, diced tomatoes with green chile peppers, green onions, ketchup, Dijon mustard, and cayenne pepper in a slow cooker.
Cook cheese mixture on Low, stirring occasionally, until the cheese is melted completely, about 1 hour. Crumble bacon over the surface of the dip to serve.
