Preheat oven to 450 F degrees. On a rimmed baking sheet, rub sweet potatoes with oil and season with salt and pepper. Bake until tender, 40 to 45 minutes. Let cool on sheet (keep oven on).
Halve sweet potatoes lengthwise; scoop out 1/3 cup flesh from each half into a medium bowl. Add buttermilk and paprika to the bowl. Mash until smooth and season with salt and pepper, to taste. Stuff sweet potato skins with the filling. (To store, refrigerate, up to 2 days.)
Arrange the stuffed sweet potato skins on the baking sheet; bake until lightly browned around edges, about 15 minutes.
Meanwhile, in a skillet, cook bacon over medium until crisp, 5 to 8 minutes. Drain on a paper towel-lined plate; crumble. Stir together sour cream and 2 tablespoons water; drizzle over sweet-potato skins. Garnish with bacon, paprika, and scallion; cut in half. Serve warm and enjoy!