Process day-old bread slices, in batches, in a food processor or blender until medium-fine crumbs. Set aside.
Peel shrimp, leaving tails on. Butterfly shrimp by making a deep slit lengthwise down the back from the large end to the tail, cutting to, but not through, the inside curve of shrimp. Remove vein. Pat shrimp dry with paper towels; set aside.
Whisk together half-and-half, sugar, and egg until sugar dissolves.
Dredge shrimp in flour; shake off excess, and dip in egg mixture. Coat with breadcrumbs, and arrange on baking sheets.
Pour oil to a depth of 3 inches into a Dutch oven; heat to 300°. Fry shrimp, in batches, 3 minutes; drain on wire racks over paper towels. Serve with Red Sauce and Tartar Sauce.