Once I put fondant on a cake I never put it in the fridge, unless it has a perishable filling. Buddy says put the cake in the cake box and then put it in the fridge, bring it out and let it come to room temp still in box and you won’t get condensation. I’ve never tried this because my fridge is not large enough for the cake box too, unless I remove all the other food.
When I was taking a class with Mike McCarey, he said he covers his cakes with a garbage bag, taping the opening of the bag to his cake board. I have tried it and it really does cut down on the condensation, and doesn’t take up any more room than the cake itself.