That would not work, because my hats have different sizes and angles, so the mask would need to be different for each type of hat.
In my case i need to find a way to make the “Hat mesh” be a mask to hide the hairs, that way each shape of hat would mask all the hairs.
I will experiment with stencils maybe there is a way, if i really cant figure a solution, i could try to make my hairs and hats skeletal meshes, but i will try to avoid it.