Separate bacon strips into stacks of 3 and firm up in freezer for 30 minutes to make them easier to cut; then cut into 1/2-in. dice. Cook diced bacon in a large frying pan over medium heat until brown and crisp, 10 to 15 minutes, stirring frequently. Strain bacon and set aside (reserve fat for another use).
Drizzle each iceberg wedge with 1 1/2 to 2 tbsp. vinaigrette, tipping to fill nooks and crannies. Season with salt and pepper. Drizzle each wedge with about 2 tbsp. blue cheese dressing, then top with several slivers of pickled onion, lots of blue cheese, and plenty of bacon. Finish with a sprinkle of chives.
Make ahead: Bacon, chilled, up to 4 days. Lettuce, blue cheese, and chives, prepped and chilled, 1 day.