Most people who race wear very little, I've seen people paddle with just a B/aid and deck. I'd would go for a rash vest, platypus/camel pack, helmet, maybe neoprene shorts or longish shorts and good booties as you do need to walk a bit to the get on and for the portage. It's later than normal and this may influence your choice.
I haven't raced it and any long distance I was on, I was more likely to be nice a warm due to liver damage to need much.
