ARFoundation Face Tracking occlusion problem - How to occlude the region of wig model that appears behind neck and shoulder region of user?

I am using Face Tracking of ARFoundation to place a wig model onto the player’s head. I have also got the physics going for the hair fringes. In order to prevent back face of wig from being visible, I’ve attached an occlusion material to mesh renderer of ARFace GameObject. The problem is that, this way only the region of wig that lies behind the generated face mesh gets occluded, and the part of wig that appears behind neck or shoulder region is still visible. Is there any way even that region is occluded?