Preheat grill to HIGH.
In a large bowl, thoroughly combine first 4 ingredients (ground beef through salt and pepper); form mixture into 4 patties.
Wrap each patty with 2 slices of bacon, crossing in opposite directions.
Reduce grill heat to MEDIUM-HIGH; grill bacon-wrapped patties (bacon ends face down) for 10 minutes per side or until burgers reach desired level of doneness.
Place each patty on a lettuce leaf; top each with tomato, onion and remaining lettuce leaf.