Combine the barbecue sauce, salsa, and vinegar in a non-reactive saucepan over medium heat, bring to a simmer, and let cook until thick and flavorful, 5 to 8 minutes. Season with salt and pepper. The sauce can be served hot or at room temperature and may be refrigerated, covered, for up to 48 hours. Bring to room temperature before serving.
Make the rub by placing the salt, brown sugar, paprika, chili powder, pepper, onion powder, and oregano in a small bowl and stir to mix.
If your brisket has a thick layer of fat, trim it to a thickness of 1/4-inch. Place the brisket in a roasting pan and generously sprinkle both sides with the rub, using about 3 tablespoons per side and patting it into the meat with your fingertips. The leftover rub can be stored for several months in a jar. You can cook the brisket right away, but it will taste better if you let it cure in the refrigerator covered for at least 4 to 24 hours.
Set up the grill for indirect grilling and preheat to medium-low. If using a gas grill, place all the wood chips in the smoker box or in a smoker pouch and run the grill on high until you see smoke then reduce the heat to medium-low. If using a charcoal grill, place a large drip pan in the center, preheat the grill to medium-low, then toss 1 cup of the wood chips on the coals.
When ready to cook, place the brisket in the center of the hot grate, fat side up, over the drip pan and away from the heat. Drape the bacon slices over the top of the meat, and then cover the grill. Cook the brisket until very tender, 5 to 6 hours or until the internal temperature reaches about 190 degrees F. Generously mop or baste the meat on both sides with the mop sauce. Wrap the brisket in aluminum foil, and continue cooking until done. If using a charcoal grill, every hour you'll need to add 12 fresh coals and 1/2 cup wood chips to each side.
Transfer the grilled brisket to a cutting board and let rest for 10 minutes. Thinly slice across the grain, using an electric knife or sharp carving knife. Transfer the sliced meat to a platter. Spoon the barbecue sauce over the meat or, better yet, serve it on the side.
Place all ingredients in a non-reactive bowl and whisk to mix. Taste for seasoning, adding more salt, if necessary.