In a small bowl, mix 2 parts Russian dressing with 1 part spicy relish and set aside.
Lightly toast the inside faces of the rye bread slices.
Heat a griddle or pan to medium heat and cook the bacon, flipping regularly, until crispy. Remove and set aside.
Warm the sauerkraut in a small amount of the leftover bacon grease until heated through.
Spread the sauce on one slice of bread (inside side). Place 2 slices of Swiss cheese on the other slice, letting the cheese slightly overhang the edges. Add 2–4 slices of bacon, then top with the warm sauerkraut.
Spread mayonnaise on the outside of both slices of bread.
Place the sandwich on the griddle over medium heat and cook until both sides are golden brown and the cheese is melted, using a basting dome if available.
