Does anyone have an experiences with Swiss meringue buttercream frosted cakes and then adding fondant pieces on the meringue. With the high humidity level where I live, i'm terrified the pieces could be heavy enough to fall down the cake when the cake was at room temperature. Anyone have any thoughts or experiences?

I use SMBC 99% of the time I make a cake. Fondant covered, BC with fondant accents, bc with GP accents...do it all. Work with a chilled cake, helps a lot. Make sure your pieces are very thin. But, if you want an indicator of how it will behave, go stand a stick of butter on end on a plate outside in the shade. If it falls down and melts....probly not a good idea. SMBC is sturdier than a stick of butter, but it's a good indicator.