Position the oven rack in the lower third of the oven and preheat to 400ºF (204ºC). Generously butter, grease with bacon fat, or spray a 9x13-inch baking dish. Set aside.
Rinse the rice in a sieve under running water, stirring and turning it. Repeat this process two more times.
In a medium saucepan with a tight-fitting lid, bring the water to a rolling boil. Add the rice and return to a boil. Stir, then reduce the heat to low as soon as it boils again. Cover with a lid.
In a large 12-inch skillet with high sides, cook the bacon until crispy. Drain, reserving 2 tablespoons of bacon drippings in the skillet. Once the bacon has cooled, crumble and set aside.
Add the ground beef, green bell pepper, and onion to the skillet. Season with salt and pepper, then cook over medium heat until the beef is no longer pink and fully cooked through.
Transfer the cooked beef mixture and rice into the prepared 9x13-inch baking dish. Add the diced tomatoes, crumbled bacon, and reserved bacon drippings, stirring until well combined. (Alternatively, you can mix everything in a large bowl first—it’s easier, but I prefer mixing directly in the casserole dish to avoid extra dishes!)
Sprinkle the shredded cheese evenly over the top.
Take a sheet of foil large enough to cover the dish and wrap over the edges. Spray one side with nonstick cooking spray. Cover the baking dish with the foil and bake for 30 minutes, until the cheese is bubbly and the center is heated through.