Place a rimmed baking sheet on the center rack and preheat the oven to 425°F (220°C). Scrub the potatoes well, dry them, and prick each a few times with a fork.
Set the potatoes directly on the oven rack and bake until the centers give easily to a squeeze with an oven mitt, 50 to 60 minutes depending on size. While they bake, cook the bacon until crisp, then crumble and set aside. In a small bowl, stir together the olive oil, kosher salt, black pepper, garlic powder, and smoked paprika.
Let the potatoes cool just until handleable, 10 to 15 minutes. Halve them lengthwise and scoop out the fluffy centers, leaving about a 1/4-inch wall of potato attached to the skins (reserve the scooped potato for another use). Brush the seasoned oil over both the insides and outsides of the shells.
Increase the oven to 450°F (232°C). Carefully place the potato halves cut-side down on the preheated baking sheet and roast for 7 to 8 minutes. Flip them cut-side up and roast another 6 to 7 minutes, until the edges are browned and crisp.
Toss the shredded cheddar with half of the green onions. Divide the cheese mixture among the skins, sprinkle with the crumbled bacon, and return to the oven just until the cheese is fully melted and bubbling, 3 to 5 minutes. For extra blistered tops, broil for 45 to 60 seconds.
Transfer to a platter, dollop with sour cream, and finish with the remaining green onions. Serve hot.