Preheat oven to 350 degrees. Line a large rimmed baking sheet with parchment; arrange bacon in a single layer. Bake until browned and crisp, turning once halfway through, 20 to 25 minutes. Transfer to a paper-towel- lined plate. When cool, slice crosswise into 1/2-inch strips.
Meanwhile, in a large bowl, whisk together vinegar and oil; season with salt and pepper. Add spinach and onion, and toss to combine. Divide among plates; sprinkle with turkey bacon and cheese. Serve with quartered eggs and Herb Toasts on the side.