POSITION rack in top third of oven. Preheat to 450F. Spray a wire cooling rack with oil and set on a large baking sheet. CUT bacon slices in half crosswise to make 18 pieces. Arrange half the bacon strips on a cutting board. Set a water chestnut on each slice and wrap bacon around it. Lay seam-side down on rack. Repeat with remaining bacon, wrapping strips around pineapple pieces. BAKE in top third of oven until tops are crispy and browned, about 20 min. Flip bacon bites and bake 5 more min. Remove from oven and lightly dab with paper towels. Set aside to cool slightly. COMBINE water with sugar, vinegar, chili-garlic sauce, cornstarch and ginger in a small saucepan and set over medium-high. Bring to a boil, then reduce heat to medium-low. Simmer until sauce has thickened slightly, about 5 min. Transfer sauce to a small bowl. Serve with warm bacon bites.