1Heat oven to 350°F (325°F for dark or nonstick pan). Grease or spray bottom only of 13x9-inch pan.
2In large bowl, beat cake mix, water, oil and eggs with electric mixer on low speed 30 seconds, then on medium speed 2 minutes. Pour into pan.
3Bake 30 to 38 minutes or until toothpick inserted in center comes out clean. Let stand 5 minutes. In large bowl, mix 1 cup whipping cream, the whole milk, condensed milk and 1/3 cup rum. Pierce top of hot cake every 1/2 inch with long-tined fork, wiping fork occasionally to reduce sticking. Carefully pour whipping cream mixture evenly over top of cake. Cover and refrigerate about 3 hours or until chilled and most of whipping cream mixture has been absorbed into cake.
4In chilled large bowl, beat 1 cup whipping cream, 2 tablespoons rum and the vanilla on high speed until soft peaks form. Frost cake with whipped cream mixture. Sprinkle with coconut and pecans. Store covered in refrigerator.