Thanks everyone for your help! All of the adding wire and other stabalizer ideas were excellent, but they were just too bulky in the longrun for a working costume that needed movement.

I ended up chopping the whole backside up into smaller spikes (which was so hard to bring myself to do), making a fleece headpiece and then gluing the spikes onto the headpiece. It fit nice, wasn't too heavy and was comfortable to wear. Although I loved the look of the back, it just wasn't working nor practical for a toddler.

I just wanted to share the end result, and let everyone know, that sometimes, it's okay to destroy something in order to fix it again.

Sometimes life takes comprise and here you came up with a really good one. Sorry our ideas did not let you realize your original design. They look adorable. I love the fact that he has a blue pumpkin for his treats.

Aren't they cute!!!!