I think Cadeausucre has a great idea. I work a lot with buttercream cakes. Before I transferred the sugar to it, I would chill the cake. This will help the icing keep it’s shape. Also: After you get the sugar on it, you can use your fondant smoother and a viva paper towel to press the sugar into the sides and to tidy it up. Hope this helps.
Psalm 127:1 Unless the LORD builds the house, the builders labor in vain.