Hagg Lake water temps

I will be doing the Hagg Lake Tri in a couple of weeks and the race info says the water temps will be in the mid 70's. The race rules state you can wear a full wetsuit if its below 75, and a sleeveless between 75 and 77. Does anyone have any experience with what type of wetsuit to use at this race? mid 70's sounds like 75ish so I'm leaning toward renting a sleeveless to be on the safe side. Any advice would be appreciated. Thanks.