Preheat oven to 400 F. Line baking sheet with parchment paper and arrange bacon slices on top. Cook 10-15 minutes, or until desired crispiness.
Prepare large pot with 2 inches of salted water and bring to rolling boil. Add lobster and steam 12 minutes. Halfway through, lift lid carefully and shift lobster to cook evenly.
Break down lobster and remove meat from shell, yielding about 4 ounces of cooked meat. Chop meat into bite-size pieces.
In large skillet or griddle over medium heat, warm butter to coat pan.
Place both pieces of bun cut sides down on pan and cook about 30 seconds until golden. Remove buns from pan and set aside.
In bowl, toss chopped lobster meat with mayonnaise and set aside.
Assemble cooked bacon, tomato, lettuce and lobster mix on toasted bun.