Preheat the oven to 350°F.
In a large mixing bowl, combine the quick oats, tomato juice, eggs, chopped onion, minced garlic, chili powder, seasoned salt, garlic salt, black pepper, and oregano, if using.
Stir until the oats are moistened and the seasonings are evenly distributed.
Add the hamburger to the oat mixture.
Mix gently until the ingredients are just combined.
Do not overmix, as this may result in a dense meatloaf.
Transfer the meat mixture to a baking pan.
Shape the mixture into an even loaf.
In a small bowl, combine the ketchup, brown sugar, mustard, dried onion flakes, and smoked paprika.
Stir until the glaze is smooth and fully combined.
Spoon half of the glaze evenly over the top of the meatloaf.
Cover the baking pan with foil or a lid.
Bake for 1 hour.
Remove the cover from the baking pan.
Spoon the remaining glaze over the top of the meatloaf.
Return the meatloaf to the oven, uncovered.
Bake for an additional 10 to 15 minutes, or until the glaze is set and the meatloaf is fully cooked.
The center of the meatloaf should reach an internal temperature of 160°F.
Remove the meatloaf from the oven.
Allow it to rest for 10 to 15 minutes before slicing.
Slice into portions and serve warm.
Cover and refrigerate leftovers.
Use refrigerated leftovers within 3 days, or wrap airtight and freeze for up to 3 months.