Light your gas or charcoal grill and set up for two zone heating, establishing the temperature at 400° - 425°F. Alternatively, preheat your oven to the same temperature.
While the grill is preheating, scrub potatoes thoroughly and pierce the skins in several places with a fork. Place the potatoes on the grill over indirect heat and allow them to roast for 60 minutes.
While the potatoes are roasting, fry the bacon squares until they are slightly crispy. Place the bacon on a paper towel-lined plate and reserve the rendered bacon fat.
Remove the potatoes from the grill and when they are cool enough to handle, cut potatoes in half lengthwise. Using a spoon, scoop out the center of each half of the potato.
Using a pastry brush, coat the skins and flesh of each potato half with the rendered bacon. Then, season the bacon-glazed skins with BBQ rub (or sprinkle with salt) and place them skin side up on a cooling rack. Return to the oven or grill over indirect heat for 7-10 minutes.
Flip the potatoes over on the cooling rack and place a slice of cheddar and Colby Jack cheese in each. Close the lid and allow the cheese to melt for five minutes. Remove them from the oven or grill and fill each potato boat with bacon pieces and scallions.
Dust with additional BBQ seasoning and serve with homemade ranch dressing or a dollop of sour cream.