Season the chicken thighs with salt and pepper. Bake in a 350-degree oven for 25 minutes. Allow to cool at room temperature. Once the chicken is cool enough to handle, cut into spoon-size pieces and set aside. While the chicken thighs bake, bring the chicken broth and neck bone to a simmer in a sauce pan over medium heat. Simmer for 30 minutes. Remove neck bone. In a large pot over medium heat, combine the flour and 5 tablespoons of the vegetable oil to form a roux. Cook the roux over medium to medium-high heat, stirring frequently, until it reaches the color of chocolate this will take about 20 to 30 minutes. Add half of the onions and half of the green pepper to the roux and sauté, stirring frequently, for three to five minutes. Add the roux mixture to the stock and bring to a simmer. Add the bay leaf. In a medium sauté pan, sauté the remaining onions and green pepper in the remaining tablespoon of oil for five minutes over medium-high heat. Add the garlic and sauté an additional three to five minutes. Add the canned tomatoes with their juice to the sauté pan and stir to combine, add this to the simmering stock and roux. Place the sauté pan back on medium-high heat and add the sausage. Sauté for three to four minutes. Add the diced chicken to the sauté pan and stir well. Sauté for two to three minutes, add this to the simmering stock mixture. Simmer the gumbo gently for 45 minutes to one hour or until flavors have combined and vegetables are tender. Season to taste with salt, and pepper. When ready to serve, stir in the shrimp and turn off the heat, allowing the heat of the gumbo to cook the shrimp. Ladle about 1 cup of Gumbo into a bowl and add ½ cup of cooked rice.