Set aside 1 cup of the baked beans. Puree the remaining beans in a blender or mash them in a large bowl; set aside. In a large saucepan, melt butter over medium-high heat. Add hot dog pieces and onion and cook 3 to 5 minutes, or until lightly brown. Add tomatoes, tomato juice, brown sugar, and hot pepper sauce. Simmer 10 minutes. Add the 1 cup reserved whole beans and the pureed beans. Reduce heat to medium-low and cook 10 to 15 minutes, or until the soup is piping hot, stirring occasionally.