An American buttercream? Confectioner's sugar, whipping cream, butter, etc. That's cool. You need to clear out a spot in the frige for this to sit after you ice it. Then when you take it out to fondant it it will sweat a bit as was mentioned upthread and that will be perfect for the fondant to adhere to it. Then get it all smoothed down and trimmed and slap it back in the frige.
The only issue I can think of is perhaps a bit of further sweating when you take the fondanted cake from the frige to 80 degrees. Just let it dry and resist the urge to swab it down, don't touch it and you'll be fine.
Do you by any chance have a secure enclosed porch? That would work too. If coyotes, mountain lions and/or bears park on your porch to get a slice then forget I said this. :)
Oh and after fondanting--no wrapping necessary. Unless you are delivering it elsewhere then I'd put it in a box.
