In a large bowl, add the sliced onions, buttermilk, salt and pepper. Stir gently to combine and thoroughly saturate. Cover with plastic wrap and let sit for one hour, stirring occasionally.
Prepare grill to medium heat. Wrap one hot dog with one strip of bacon and repeat with the remaining dogs and bacon. Place on the grill and allow to cook until the bacon is crispy and the hot dogs are thoroughly cooked, around 15-20 minutes. Remove from direct heat and keep warm until ready to plate.
In a large pot with several inches of canola oil, heat to 350 degrees. Add the flour, garlic powder, chili powder, salt and pepper to a large, deep bowl and dredge the soaked onions until coated. Tap off the excess coating, then submerge in the oil and gently pull large clumps apart with tongs or a heat-proof fork. Allow to fry for 2-3 minutes, or until golden brown and crispy, then remove with a slotted spoon and transfer to a paper towel-lined plate to drain. Repeat with remain onions until done.
Add one bacon wrapped hot dog to each hot dog bun, then slather with the Smoked Bacon BBQ sauce. Top with the cheddar cheese and a heaping pile of onion strings. Serve immediately.