Particle System mesh, outer edge only

This is a question that has gotten no reply from about a year ago, which is at this link:

As a recap, I am trying to create a particle emitter that only emits particle along the edge of an odd shape ( not a square or a circle ). Every time I import a mesh for this shape, I have the same problem that the previous person has: namely that the odd shape is cut into triangles ( expected ), but the particles emit from all edges, including the inner edges of the triangles. I only want the outer edges ( which seems to work with the default quad and circle meshes within Unity itself ).

Is there a way to ensure either A) the inner edges are ignored, or B) a way I can import an odd shape that isn’t composed of triangles.

Create a separate mesh that is comprised of the areas you only want it to emit from. Assign that to the particle emitter and switch it’s mesh renderer off.

Hmm, is there a secret to disabling the mesh renderer on imported meshes? Everything I’ve tried has resulted in having the mesh renderer “in the grey” and unselectable.