Preheat oven to 325°F.
Oil a baking sheet.
Rub skins with oil.
Place potatoes on baking sheet. Place in preheated oven and bake until potatoes are tender, about 1 hour.
Remove baking sheet from oven and allow the potatoes to cool enough to work with. Leave oven on.
When cooled, cut each potato lengthwise into halves. Scoop out centers, leaving 1/2-inch thick layer of cooked potato on skins.
Place skins, skin side down, back on baking sheet, spacing 1-inch apart. Sprinkle with salt and pepper.
To a medium bowl, add bacon, both cheeses, parsley and cayenne. Stir to blend.
Fill each potato boat with a tablespoon or two of bacon/cheese mixture.
Place back in hot oven. Bake until skins are crisp and cheese mixture melts, about 25 minutes.
Transfer skins to serving platter.
Sprinkle with green onions. Top with a dollop of sour cream.
Serve with additional dipping sauces, if desired.