To make the honey mustard dressing- in a bowl whisk together mayonnaise, mustard, honey, and lemon juice. Season with salt and pepper. Store covered in the refrigerator until needed.
Season chicken breasts on both sides with salt and pepper. Cook the chicken using your method of choice (grilling, stovetop, oven) until fully cooked (the internal temperature has reached 165 degrees). Allow the chicken to cool and chop it into small chunks. Chop the cooked crispy bacon until pieces. In a large bowl mix together the chicken and bacon pieces.
Pre-heat the oven to 300 degrees. Split the sub rolls and lay them onto a baking sheet. Spread about 1 tablespoon of the honey mustard dressing onto one side of the inside of the sub roll. Fill each sub roll with even amounts of the chicken and bacon mixture. Top with 2 slices of Swiss cheese. Place into the oven and bake at 300 degrees for 10 minutes (or longer if you want them toasted more).
Remove from the oven. Top the subs with 2 slices of tomato, 2 slices of onion, 1 piece of lettuce, and additional honey mustard sauce.