How to Add a Head?

Hi...

I'm going as "Inbred Riding Hood" for Halloween this year. I would like to add a second head to my shoulder but I'm having some trouble figuring out how to do this. I know I need a mask and a Styrofoam mannequin head....but after this I'm kind of lost. I'm looking for something easy and not too heavy, I'll be wearing it for about 8 hours or so. I have a friend who can make me a double hooded cape.

Thanks for any help!

Michelle