Help locating cross bracing in Prius v roof?

I am in the planning stages of building and mounting a custom-all-the-way roof rack to my just acquired Prius v, and would like (ideally without pulling the headliner down, though advice on how to accomplish that would be most welcome) to know where exactly the cross braces that span the roof are? I’d like to drill in the exact center of those if possible to take advantage of the extra strength provided by the extra layer of steel present in those locations.
This post started me down this road, but posts there art generating replies: https://priuschat.com/threads/prius-v-lowercase-v-for-the-prius-v-wagon-five-custom-yakima-54-track-and-diy-instructions.149425/

Thanks very much!