Line a baking sheet with wax paper. In a large bowl, combine ground chicken, salt, and pepper; gently combine with hands. Lightly coat hands with nonstick cooking spray; form chicken into 8 (31/2-inch) patties. Place patties on prepared baking sheet. Cover, and freeze for 20 minutes, or until slightly frozen (freezing will make removing patties from wax paper easier).

In a small bowl, combine peach preserves, mustard, water, and vinegar. Reserve 1/2 cup peach mixture.

Spray a grill rack with nonstick, nonflammable cooking spray. Preheat grill to medium-high heat (400° to 450°). Place patties on prepared grill rack. Grill for 2 to 3 minutes on each side, or until no longer pink in center. Brush with peach mixture; cook for 1 minute. Remove from grill. Place buns, cut sides down, on grill; grill for 2 minutes, or until grill marks form.

Fill each bun with 1 chicken patty, 1 piece bacon, 1 onion slice, and 1 tomato slice. Serve with reserved peach mixture. Garnish with dill pickle slices, if desired. Serve immediately.