I got some Hart F17 WC's and they have no recommended mount line or center line. I sent a request to the contact us on Harts site but have found nothing online that isn't relative to some recommended point.
They're fun as hell but the demo bindings that came with them have caused me to ragdoll more than once with the dins nearly maxed out (11). I also need to find 75mm brakes for the pivots I plan to put on them.
The Harts are a bit wider than modern ID1 or Faction bump skis but they're still crazy maneuverable in the bumps.