Preheat oven to 350 degrees or 325 for glass pan. Drain pineapple, reserving juice. Combine juice, coconut milk, rum and sour cream. Add combined liquids, eggs and coconut to cake mix. Stir enough to moisten mix. Pour into prepared 9" x 13" baking pan. Bake 40 minutes, or until springs back in the middle.
When cool beat together cream cheese, powdered sugar and vanilla. Spread on top of cake. Top with toasted coconut. Keep refrigerated.