When i was asked to make a carrot cake with cream cheese frosting and fondant for a wedding cake i researched if it was ok to fridge, i got so many varied replies from the internet and cake decorating shops about putting fondant in the fridge, some said yes, some said no... one even told me to use something else instead of cream cheese frosting so i wouldnt have to worry about leaving it out ...
I ended up using the cream cheese frosting and fondant and put it in a box in the fridge (it was a very hot week of 35+ degrees C every day) there was no way i was risking leaving it out.
Just make sure you take it out of the fridge about 10-15mins before serving to make sure the 'sweat' has had time to dry. If you do not touch the cake when it is sweaty it will dry with no problems and you wont even be able to tell.
If the reception is air conned then you might? be able to leave it out once set up, but definitely overnight i would be putting it in the fridge.
I just made sure to remove the gumpaste flowers before putting the cake in the fridge as i wasnt sure how they would be after it was taken out.
The cake i put in the fridge was the cherry blossom cake in my photos and turned out fine, the frosting didnt turn the fondant to mush or goo or anything like that, it was just the same if i had put buttercream underneath the fondant