I've never filled a cake before using whipped chocolate ganache (or even made it, for that matter ;))  Do I need a damn with it, or is it stable enough once cooled to hold up the top layer without bulge?  I plan to use a 2:1 ratio of heavy cream to chocolate. I will also be covering and decorating with MMF and modeling chocolate.

Any thoughts are appreciated! 

whipped ganache is very stable--no worries