I have a client who likes whipped icing only. I can never seem to get the edges smooth. Does anyone have any tips or ideas?

I've done two ice cream cakes where they wanted a 'kool-whip' type icing. I found a recipe that added pudding to kool whip (along with other ingredients) and the only way I could get it smooth was to wet the spatula with hot water and smooth and wet and smooth.... and freeze and continue until it was as good as it would get. After you take it out the freezer, you can wet the spatula with hot water and smooth, then add more icing if you need to. This worked for me, I also told her that it wouldn't be as smooth as when I use butter cream, Good Luck!