Mix ground beef, chorizo sausage, egg, bread crumbs, green chilies, onion, barbecue sauce, ketchup, and onion soup mix in a large bowl until well-combined. Cover and refrigerate overnight.
Preheat an outdoor grill for medium heat. Firmly pack the meat mixture into a 9x5-inch loaf pan, and cover with aluminum foil.
Place the covered loaf pan on the grill away from direct heat. Cook for 30 minutes, then carefully remove foil and drain grease. Cover the pan with the foil, and return to the grill. Continue cooking until the meatloaf is no longer pink in the center, about 20 minutes more. An instant-read thermometer inserted into the center should read 160 degrees F (70 degrees C).
