check with mccalls again...they usually have very strict instuctions on how they want it packaged and if you add things you shouldn't it might be returned, or if you don't have all the items they want included in the package.
make sure you put your address inside the package too...but follow their rules. each show/contest/ entry place has it's own requirements for sending in some even tell you what carton or packaging you can or can not use.