Heat your grill for medium-high heat cooking, about 400 degrees F. Cook the bacon on a sheet pan lined with foil until crisped, about 15 minutes. Remove from the heat to cool so you can chop them.
Toss the potatoes with the olive oil and season generously with kosher salt. Cook the potatoes in a cast iron skillet on the grill until fork tender and browned, about 20 minutes. Turn the potatoes once, about half way through the cook.
When the potatoes are done, remove them from the heat to cool slightly. Chop the bacon, then use a mallet or heavy bottomed glass to smash the potatoes. Return the potatoes to the skillet and season with the Salt and Pepper + Sour Cream and Onion seasoning. Top with the cheddar cheese and bacon and return to the oven until the potatoes are crisp and the cheddar cheese is melted.
Top the potatoes with more sour cream and the chopped onion and let them cool for a second before you dig in.