We have a small ring on both sides of the trampoline (1cm diameter) about 60 cm from the rear beam (4th or 5th screw on the Nacra).
There is a piece of bungee that goes from side to side via the dolphin string (to keep it from dragging).
On both sides of the bungee there is a loop where a knot on the spinsheet attaches to, this way you have separate sheets which is much easier for the crew.