Preheat the oven to 400 degrees F. Divide the naan between 2 foil-lined baking sheets and bake until crisp, about 10 minutes.
Meanwhile, cook the bacon in a large nonstick skillet over medium heat, turning occasionally, until crisp, 8 to 10 minutes. Drain on paper towels, then crumble. Remove 1 tablespoon bacon drippings from the skillet and reserve for frying the eggs.
Add the onion to the remaining drippings in the skillet and increase the heat to medium high. Season with salt and pepper and cook, stirring, until browned and tender, 5 minutes. Add the tomatoes and cook until most of the liquid evaporates, 3 to 5 minutes. Season with salt, pepper and hot sauce.
Spread the onion-tomato mixture on the naan and top each with 2 slices cheese. Return to the oven until the cheese melts, 3 to 5 minutes.
Meanwhile, heat the reserved bacon drippings in the empty skillet over medium-high heat and crack in the eggs. Season with salt and pepper and cook until the whites are just cooked through, about 3 minutes.
Top each flatbread with a fried egg; sprinkle with the bacon. Toss the greens with the vinegar; season with salt and pepper. Serve the flatbreads with the salad and more hot sauce.