I personally like a smooth texture to my meatloaf (that's how mom makes it too). So.... In a food processor I like to add my veg (red bell pepper, carrot, onion, garlic, oatmeal) and grind it smooth. I then like to soften the veg on the stove before adding it to the meat. I've used turkey but I prefer 80/20 beef.
Also, throw away your meatloaf pan and switch to a 9x13 cake pan. Form the loaf in the center of the pan so that it doesn't touch the edges, it should look like a football. This way the grease will wick away from the meatloaf but the natural juices will stay inside.
For the topping.... I'm from the southwest so we used a ketchup, brown sugar, pepper, based sauce where others use a brown gravy.... Make what you like.
Leftovers! My favorite!
Take the meatloaf, smash it with a fork, and add it to some cooked penne. It is so good! Maybe add some fresh mozzarella or parm on top!
The ultimate man sandwich also starts with leftover meatloaf. Toast some bread, one half gets spread with miracle whip, the other half gets a healthy dose of ketchup. Add a thick slice of meatloaf, plop a egg fried in butter on top, add the top piece of toast and chow down with knife and fork!