I've been using this recipe from chef John Dougherty at the Waldorf for 18 years. It's Dh's favorite, especially cold in a sandwich with lots of Dijon mustard. This recipe is easily doubled and can serve 40 at a buffet.
Trim crusts from bread and cut slices into 1/2" dice, put in large bowl and add milk and tomato puree, let soften while preparing vegetables.
In skillet heat oil, saute onions until softened, add bell peppers and garlic, increase heat and saute until peppers are softened but still brightly colored and onions are golden.
Mix bread in bowl, add vegetables, meats, and remaining ingredients except bacon.
The meatloaf can be made a day ahead and refrigerated at this point.
Form loaf on rimmed baking sheet, arrange bacon crosswise over meatloaf and tuck edges underneath, bake at 375° for 70 minutes or until internal temp is 180°F, remove from oven and pour off grease, let stand 10+ minutes before slicing.