It seems to me that the Recretec double rails are meant to cradle the entire straight section of the raft tubes, therefore might not fit properly on the elliptical side tubes of the "D" series rafts. I would assume that a portion of the frame, either at the ends or the middle, would not be in contact with the tubes. Maybe a non issue, but thought I would mention it.
They sure are sweet looking frames. Love the clip in dry boxes, is the mounting really bomber enough that you don't have to strap the boxes in also?