Jeff,
My experience has been that breakages in this kind of event are somewhat rare. We usually take a little extra time during setup before a week long event like this to make sure every ring and pin are taped in place and that all lines are fresh with no chafing. We have the same spares that we usually have on hand for a weekend event; hot stick, spin pole (if possible), spare rudder blade, spare daggerboard. Backup sails (particularly a spinnaker) are nice if you have them too. With the number of people participating, somebody has a spare for whatever you need.
I would also add (and this depends on your boat fixing skills)
White gelcoat filler (or appropiate colours) in case of little dinks to hulls and plates
White gelcoat (or appropiate colours), micro ballons, chopped stand, glass tape and glass matt (for bulk filling of bows for more major chunches)
Epoxy
Old (plastic) Ice cream tubs (excellent for making backing plates for more major, short term, non load bearing) repairs.
(if you can store it somewhere dry, some Balsa wood, again excellent for the above).
Files, hacksaws, 200/400/600/800/1200 wet and dry, "thinners" (and I can never remember what they are as I never have them), Knives, Spatulas for applying Gel / gelcoat, stirrers and cups to mix in (Wooden "Coffee" stirrers from well known junk food chain beginning with Mc are ideal, also ask for a job lot of paper cups - don't ask, don't get!)
Most of the above is only really required if you think you have a chance of mending bigger (usually bow shaped) holes in the side of boats. I would be very wary of reparing anything that is "load bearing".
