Update: after further consultation with the other race organizers, it's become clear that the additional 'fastest' :15 bonus is likely to be more problematic than it's worth, as it leads to questions about what happens if the fastest speed is part of a slower (and hence discarded) run, as well as the potential for other shenanigans on the last day.
Racers should have more transparency around where their times stand in the ranking, rather than face the prospect of a random CMDR shuffling the podium at the last second with a half hour run that hits 20c.
Also added this note to the race description, because I overlooked it, too:
NOTE: According to a new rule introduced for the 888 Championship, any racer who places in the top 5 in unlimited will have that ship "locked" and will no longer receive more than 15 points (6th place) in any following race that season during which they enter the same ship type. This should encourage the top racers (last season this would only affect 10 racers) to spread their wings more and explore a variety of vehicles for mayhem. If you do not place in the top 5 this does not affect you. If you do, don't use that ship type again in unlimited for the season.