Spread cornbread cubes level in a 10- by 15-inch rimmed pan. Bake in a 375° regular or convection oven until lightly toasted, 20 to 25 minutes, turning cubes occasionally with a wide spatula.
Meanwhile, lightly butter one side of a 12-inch-long sheet of foil. Lay foil flat on a counter, buttered side up.
In a 10- to 12-inch frying pan over high heat, stir 2 tablespoons butter, pecans, sugar, and 2 tablespoons vinegar just until liquid is evaporated and sugar mixture is dark brown, 4 to 5 minutes. Scrape nuts onto foil and push apart.
Rinse frying pan and wipe dry. Return to medium-high heat and add bacon; stir often until well browned, 5 to 8 minutes. With a slotted spoon, transfer bacon to paper towels. Discard all but 2 tablespoons fat from pan. Add onion; stir often until limp and lightly browned, 5 to 8 minutes. Add remaining 2 tablespoons vinegar and stir until liquid is evaporated, about 1 minute. Add thyme and nutmeg and mix; add parsley and stir until wilted, about 1 minute. Remove from heat.
Pour toasted cornbread into a large bowl. Add onion mixture and mix well; add 2 cups broth and mix well. Mix in 1/2 cup candied pecans and salt to taste.
Return cornbread mixture to 10- by 15-inch pan; spread level. Bake in a 375° oven until hot, about 10 minutes. If you prefer a more moist dressing, stir in more broth.
Spoon hot dressing into center of drumstick crown roast; garnish with remaining pecans.