Since you use a recipe with high ratio shortening you should be fine with the all buttercream option. As long as the cake is in the shade you should be fine with the white chocolate ganache options. I use a buttercream with high ratio shortening and deliver cakes to outdoor wedding receptions all the time. I deliver the cakes (or cupcakes) 2 hours before the reception starts so I am done before any guests arrive. There has never been a problem.
9/16/14 at 9:39am