If you don't think it will hold up to the weight of the fondant what alterations can be made to make the cake sturdier without altering the flavor much. This is not my recipe, but a friend's. Thanks for any suggestions.

Fresh Grapefruit Cake
2/3 cup butter, softened
1 3/4 cup sugar
2 eggs
3 cups cake flour
2 1/2 tsp baking powder
1/2 tsp salt
1/2 cup grapefruit juice
3/4 cup milk
1 tsp grated grapefruit zest
1 1/2 tsp vanilla

Cream butter; gradually add sugar; beat well. Add eggs one at a time. Combine flour, baking powder, and salt in small bowl; add to mixer gradually, alternating with grapefruit juice, beginning and ending with flour mixture. Gradually add milk, then zest and vanilla. Pour into two buttered/floured 9" round cake pans. Bake at 350 for 30 minutes or until cake tests clean. Cool 10 minutes in pan before moving to wire rack to cool completely.