Clean and rinse duck breasts thoroughly in cold water. Cut into 1/4-inch slices and place in a resealable plastic bag with water and salt. Refrigerate for 2 to 3 hours. Remove from bag and rinse again under cold running water.
Combine duck, ground chipotle pepper, vinegar, Worcestershire sauce, monosodium glutamate, garlic powder, and hot pepper sauce in a resealable plastic bag. Refrigerate until well marinated, 2 to 3 hours more.
Fill jalapenos with pepper Jack cheese and cream cheese. Top with marinated duck. Cut bacon strips in half and wrap each stuffed pepper with a bacon strip. Secure with a toothpick.
Preheat an outdoor grill for 400 degrees F (204 degrees C) and lightly oil the grate. Cook jalapeno peppers, flipping once or twice, until bacon is browned, about 15 minutes.