Step 1Heat the oven to 450 degrees.
Step 2Fry the bacon in a skillet over medium heat until crisp, 6 to 8 minutes. Transfer to paper towels to drain, then crumble.
Step 3Melt the butter in a skillet over medium-low heat without stirring. When it's completely melted, reduce the heat to low and simmer 5 minutes. Skim the white foam off the top. Pass through a fine-mesh sieve, reserving the clear yellow liquid and discarding the solids.
Step 4Shuck the oysters, straining and reserving the liquid. Discard the shallow halves of the shells and scrub and dry the deep halves. Pour the rock salt into large baking dishes and arrange the shells on top. Place 1 oyster in each shell. Sprinkle the oysters with the bacon. Mix the reserved oyster liquid with the clarified butter, ketchup and bell pepper and pour equal amounts over the oysters. Sprinkle the tops with the cheese. Bake 5 to 7 minutes. To brown the cheese, place under the broiler 2 to 3 minutes. Serve immediately.