Thanks for the input. I only recently joined the VRay clan, so I'm not familiar yet with all the tools in it.
However, if it's render-time only, it won't solve my need as I'm trying to efficiently cull hidden geometry because the final output is a game engine, not rendering. We are currently using Max's native Boolean and ProBoolean, but they are often buggy and destructive. So I was thinking more of a setting or modifier or utility with that in mind.