Can you cover a whipped cream cake with fondant? If so, what is the best way to do it?

I maybe wrong, but i would guess no. I think the weight of the fondant will squish the whipped cream and make a hugh mess. Now i suppose you could fill the cake with whipped cream, but that may get squishy on you too.

Whipped cream is not stable enough to hold up the fondant. Peg818, you're right, the fondant would just squish it.
I suppose of you wanted to fill your cake with whipped cream, you could make sure you have a thick dam (i.e. stiff Buttercream) so it won't squish out while rolling the fondant on.
Hope that helps you Katie.