If you prefer your potato salad with skin, scrub the potatoes under cold running water with a vegetable brush.
When ready to cook, start the Traeger grill on Smoke with the lid open until the fire is established (4 to 5 minutes). Set the temperature to 350F and preheat, lid closed, for 10 to 15 minutes.
Lay the bacon slices on the grill grate perpendicular to the bars. Arrange the eggs and potatoes on the grill grate as well. Prepare a pan or bowl of ice water.
In the meantime, make the dressing: In a mixing bowl, combine the sour cream, mayonnaise, pickle relish, if using, mustard, Traeger Prime Rib Rub, and vinegar. Taste the dressing, adding more mustard, vinegar, or salt and pepper as needed. The dressing should be very flavorful. Stir in the cheese and scallions. Set aside.
Cook the bacon until it is golden brown, 20 to 25 minutes; it will crisp as it cools. With tongs, transfer it to paper towels to drain, then crumble.
Check the eggs when the bacon is done: Remove one egg from the grill and plunge it into the ice water. Peel and slice in half to check for doneness: The yolk should not have any rawness in the center. If the egg is cooked through, transfer the others to the ice water and let cool slightly before peeling and finely dicing.
Increase the temperature of the grill to 400 and continue to bake the potatoes for another 20 to 30 minutes, or until they are tender but not mushy. Transfer to a wire rack and let cool slightly.
Peel the still-warm potatoes, if desired, or leave the skins on. Cube the potatoes and transfer to a large mixing bowl. Add the crumbled bacon and the diced eggs. Pour the dressing over the potato mixture and stir gently with a rubber spatula to combine. Taste again for seasoning.
Transfer to a serving bowl and dust with paprika and top with parsley. You can serve as is, or cover and chill.