I have an upcoming project for a bottle of champagne cake. I plan to have the bottle laying down and the cake and buttercream will be champagne flavored. I typically cover my cakes in ganache prior to fondant. I really don't want the ganache to overpower the champagne flavors. I don't necessarily need to cover in fondant. It's just what came to mind first, because of the dark champagne bottle's color. Any suggestions?

Is it even possible to add champagne to white chocolate ganache?

I don't know if you can add champagne of ganache or not.  Liz Marek makes a water ganache that works beautifully, so maybe.  White chocolate is such a mild vanilla flavor, I doubt it would over power you cake flavor anyway.

Thanks @SandraSmiley! I think I'll proceed with just white chocolate ganache :-)

Best of luck!  It sounds delicious.