Preheat oven to 450°F. Prepare potatoes by scrubbing clean and piercing with fork in several places. Rub olive oil over potato skins and place in oven, directly on rack.
Bake for 60-75 minutes, until potatoes are crispy on the outside and soft on the inside. When lightly pressed, potatoes should give under the pressure.
Let potatoes cool completely. When cooled, cut each potato in half, lengthwise.
Make potato boats by carefully scooping out the interior flesh, leaving the skin plus approximately ¼ inch of potato flesh intact. Set aside 6 boats and discard the remaining 6.
In a large bowl, combine potato flesh with sour cream, 1 cup of cheese, butter, milk, and bacon. Mash with a potato masher until combined. Spoon mixture evenly among the 6 potato boats.
Place in a large, oven-safe casserole dish, sprinkle tops with remaining cheese, and bake in a 350°F oven for approximately 20 minutes.
*To make ahead: complete all steps prior to the final baking. Place loaded potatoes in an airtight container and refrigerate until 1½ hours prior to serving. To serve, remove potatoes from refrigerator, place in a large, oven-safe casserole dish and let potatoes come to room temperature. Bake in 350°F oven for approximately 20-30 minutes.