Preheat the oven to 300 degrees.
Chop all the vegetables and set aside. Mix the Fixins' in a small bowl making sure to break up any lumps from the brown sugar. Set the Fixins' aside.
In an oven-safe heavy Dutch oven with a lid, fry the bacon over medium heat until almost crispy and plenty of fat has been rendered. Remove the bacon from the pan and set aside. Make sure to leave the bacon grease in the Dutch oven.
Continuing on medium heat, sauté the yellow onions and peppers in the bacon grease until starting to caramelize. Don't rush this step, it will take about 20 minutes. See NOTES.
Add the garlic and stir until aromatic, about 2-3 minutes.
Add the beans and mix well. Increase the heat until it comes to a simmer for a few minutes.
While it's simmering, fill one of the cans with water. Pour the water from can to can to capture all the juice. Set aside. See NOTES.
Add the Fixins' and combine completely. Add about ½ can of the water and increase the heat to bring it to a boil, set the remaining water aside. Cook on a slow simmer for about 5 minutes. Add back some or all of the bacon.
Place in a 300 degree oven, covered for about three hours total. Stir every hour or so making sure to scrape the beans off the side and bottom, Add more water from the reserved can depending on how thick you like your beans.