Dragon fins help needed

Hello!

I'm working on a dragon head on a balaclava. The dragon has a large fin on his head that goes down the neck to the back. I'm having trouble figuring out how to make these. I do want to use EVA foam mat for sturdy spikes and a thinner foam for the membrane. Glueing them down to the balaclava and then covering them with fleece (membrane) and vinyl (spikes), but since the balaclava is stretchy and the head is slightly smaller than the client's head I'm not sure what will happen if it stretches.
Was also thinking about making a pattern of the foam, then take the foam off and just sew the fins to the hood, shove the foam parts in for stability, I don't want the fins to fall to the side. But I'm not sure how to attach the fleece to the vinyl spikes, it would be very hard to turn them right side out.


Here's some pictures of the project:



first 2 spikes are attached to foam, 3rd one and the rest to balaclava.




The rest would be attached like this.




The neck is be much longer than the balaclava is, the spikes go down all the way to the end. Again, no idea how to do this.


Anyone got any ideas? Redlines or sketches are welcome too!