You can substitute up to 1 1/2 cups of all-purpose flour with whole wheat flour. Instead of applesauce you can use vegetable oil as well. Increase the sugar amount up to 2 cups if you have a sweet tooth.
You will need about 1/2 the rind of 1 watermelon to get 3 cups of shredded watermelon rind.
You can make muffins as well with this recipe--fill muffin cups about 2/3 full and bake for about 30 minutes.