PREHEAT oven to 375°F. Toss sweet potatoes and onions with dressing and 1/2 tsp. of the thyme. Arrange in 15x10x1-inch baking pan sprayed with cooking spray. Bake 10 min.
MEANWHILE, combine stuffing mix and water. Cut each tenderloin diagonally into thirds. Push vegetable mixture to edges of pan. Spoon stuffing down center of pan; top with meat. Sprinkle remaining 1 tsp. thyme over meat.
BAKE 45 to 50 min. or until cooked through (160°F).
***NOTE: I am not using Stove Top Dressing as it has much too much sodium, I will be using regular bread crouton cubed stuffing mix which comes with a seasoning packet. This will cut the sodium in half.