if Friday's not a huge issue, then why not a 4 day event? 1/2 day sailing on Friday (pm) and Monday (am)?

Then, you could have some additional flexibility if any of the days have bad weather (heavy or nonexistent wind). And throw in that "average score" thing for those who can't make the early (Friday) or late (Monday) session.

But it does add more logistics costs... So maybe fun races or a distance thing on Friday?