The 5.5SL that I had used a track along the foot of the sail. A car ran on that track that the mainsheet system hooked to. Less rotation upwind meant the car was pulled forward on the track running along the foot of the sail (It had a line and cleat that adjusted where the car was on the track). The track only ran for about 18 inches or so on the foot/aft end of the sail.

I have a good picture, but it is too large a JPG to post - but this was standard set up on most 5.5 SLs.