I'd just epoxy it flush with the surface of the ski. Used west systems and added some chopped fiberglass fiber for strength and it worked insanely well. Also got a base grind and it looks amazing. PTex doesn't bond very well to cured epoxy which is why it's not great for core shots on its own.
If you really wanna have a PTex surface there, you can cut out the base material surrounding the core shot, use it as a stencil to cut a fresh piece of base material that covers the core and edge teeth, then epoxy that in there. Make sure to check that it's a good fit before putting epoxy in there.
Also when epoxying, I recommend using masking tape cause that shit gets in places you won't want it.