@Assiduity, have you considered putting something in the middle (yarn, padding, etc.) and wrapping the wig around that to add some shape to it? I once saw a Rapunzel wig tutorial that did that and it seemed to work out pretty well. I can't find it right now but I think it was on deviantart.
"I know I have the body but of a weak and feeble woman; but I have the heart and stomach of a king, and of a king of England too."