hi! I'm a newbie, and I'm trying to get things in order for tastings for cupcake towers for summer weddings. Currently (fall/winter), I use a buttercream icing made with 1/2 butter, 1/2 hi ratio shortening. It holds up well. Will this also hold up well in warmer weather with the butter in it? Or should I switch to just the hi ratio?
Will a whipped icing hold up, too? How about a faux swiss meringue made with marshmallow creme and hi ratio? (the recipe actually calls for butter, but I know that'll melt, so I thought I'd try it with hi ratio instead).
I guess what I'm looking for is someone to advise me on which icings hold up best in the heat and don't melt or "sweat." Sometimes in the summer here it gets hot and humid!

Thanks! Maria