Been quite a while since my wife or i have made meatloaf. We usually use half ground deer and half ground sirloin, a lb of each. Several recipes above are similar to what we use. Off the top of my head without asking my wife or looking for the recipe:
2 eggs
Half cup bread crumbs
Tbsp worcestershire sauce
Lipton beefy onion soup mix, I prefer real onion but admit the packet is quicker and easier
Tomato sauce
Had never used mozzarella, but going to have to give that a try now.
Sometimes we use ketchup glaze, and other times go with brown gravy, good either way.