Custom elytra model.

I have been doing some testing and I was wondering if it's possible to change the size and the shape of the elytra outside its texture box and how to change it. As seen in the picture you have about this much space and even that isn't all being seen in the texture. All custom elytras I have found look basically the same because of these restrictions.
I want the elytra to be bigger and to use a more complex model. I am just asking if anyone knows if this is even possible and if there is any documentation or anything I can read to understand how to do it. 
Thanks to anyone who can help :D