Just happened to be looking through some old issues of PBO and noticed Andrew Simpson wrote a piece about a flopper stopper that he had on his boat Shindig. PBO December 2006
it consisted of an 8mm thick equilateral triangle of GRP with sides 800mm long ( corners rounded off) One corner is weighted with a lead lump and a three leg bridle rises to an attachment point. He rigged it using the spinnaker pole or the swung out the main boom. He lowered it as deep as possible. His remarks were that it "was cheap, convenient to stow and please believe me - very valuable contribution to comfort - could anybody ask for more?" He obviously thought this worked very well!
The picture in the mag looked similar to that in the link on post 25 "Make your own flopper stopper" pinterest.com