1. Soak the kidney beans in a large pot with enough water to cover (about 8 cups) for at least 6 hours or overnight. Drain and rinse the beans; set aside.
2. Cook the bacon in a large soup pot or Dutch oven over medium heat until rendered and crispy, about 8 minutes. Remove with a slotted spoon to a paper-towel-lined plate and set aside. Add the celery, onions and bell peppers and cook until softened slightly, 8 minutes. Add the beans, ham hocks, bay leaves, thyme, black pepper and cayenne. Add the stock, making sure the beans and vegetables are covered by about 2 inches of liquid; add more stock or water if needed. Bring to a simmer, uncovered, and cook, stirring occasionally to prevent scorching on the bottom of the pan, until the beans are tender and creamy in texture, 2 to 2 1/2 hours. Add additional stock or water as needed to keep the beans submerged in the liquid.
3. Remove the ham hocks, bay leaves and thyme stems. Remove the meat from the ham hocks and shred into a bowl; set aside. Crush the beans with a potato masher, leaving the mixture chunky with some whole beans. Stir in the reserved bacon and shredded meat. Add the hot sauce and salt to taste.
4. To serve, garnish with scallions and serve with white rice.