Trim fat from meat. In a small bowl combine sugar, chili powder, salt, cumin, black pepper, and cayenne pepper; reserve 1 teaspoon. Sprinkle remaining spice mixture evenly over both sides of meat; rub in with your fingers; set aside. In a medium bowl toss the nectarines with the reserved 1 teaspoon spice mixture and water; set aside.
For a charcoal grill, place bacon slices in a large cast iron skillet. Place skillet with bacon on the rack of an uncovered grill directly over medium coals. Grill 8 to 10 minutes or until bacon is crisp-cooked and browned, turning very frequently. Carefully remove skillet from grill. Remove bacon from skillet and drain on paper towels.
Place steaks on the grill rack directly over the coals. Grill until desired doneness, turning once. (Allow 4 to 6 minutes for medium-rare doneness or 5 to 7 minutes for medium doneness.) Place nectarine wedges directly on grill rack along side the steaks the last 3 to 5 minutes of grilling until nectarines are lightly browned and warmed through, turning often.
Transfer steaks to serving plates and top each with a slice of bacon and 4 nectarine wedges. Makes 4 servings.