You can post process them as well sure, but doing proxy geometry as a seperate mesh is pretty useful. I use Unreal and Unity style naming conventions and pull the meshes out for post processing when cooking to engine formats. eg SM_ static mesh, PHYS_BOX to process as a box… but you can make spheres, cylinders, actual proxies, etc.
I normally just support box meshes as all the primatives by mesh name for that, and some extra ones for like saying use for SDF.
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