I have a client who has designed her "dream" wedding cake. It is similar to this cake but with flowers and ruffles on the vanilla side. My concern is the chocolate side...

 I have made the tuxedo cake in buttercream , and it came out great,  but never in fondant. I am VERY concerned about pouring ganache over fondant. She insists on fondant and not buttercream. Anyone have any ideas or experience pouring ganache over fondant? Won't the warm / pourable ganache break down the fondant? How long in advance would you pour it on there? Please help. Thanks!