Hey Laury,
Back in the day, before free surfing was popular, Shred Stixx introduced their original shape. It's a pintail gun. Folks would shorten the rope up a bit, I think that Jerry recommends something like 20 feet and then you ride at around 20+ mph. It's certainly a fun alternative and later when you get better, the turns feel like you riding double overhead at Jaws.
Not that know what that feels like, but I have a good imagination.
We've done some line riding at wakeboard speeds and it's an enjoyable pasttime - certainly doable. IMO, it does offer more stability than a wakeskate, especially of your riding the board with a tri-fin or thruster configuration, however the down side to that was it was REALLY a chore to turn the board.
The original shred stixx
page