Back in the 60s someone wrote in Soaring about tying two-by-fours
along the tops of wings to act as spoilers. I've never seen it, but this
is strictly a "for at-home" solution if it works. Boards would need to
be stabilized in some way, of course.

At 23:05 13 August 2008, wrote:
There is no hard data on tie down strength. Just plan for the worst.
PolyPro will lose most of its strength rapidly from UV. Good covered
climbing rope and locking carabiners are the best bet.