Preheat your oven to 325°F.
Adjust your oven rack to the lower-middle position to ensure even cooking.
In a large skillet, fry the halved bacon slices until partially cooked but not crisp.
Remove the bacon and drain on paper towels.
Add diced onion and green pepper to the bacon drippings in the skillet.
Sauté until tender for about 5 minutes.
Stir in the pork and beans, barbecue sauce, brown sugar, vinegar, and mustard.
Mix thoroughly to combine all the ingredients.
Transfer the mixture to a baking dish and lay the partially cooked bacon slices on top.
Bake in the preheated oven for 2 hours until bubbly and thickened.