Some people are awfully preoccupied with shrinkage...

I think I'd rather spend my time worrying about the 9.5 miles of running which will be involved in this race, no easy feat, esp. with the sand ladder. Unless you plan on going commando underneath the wetsuit, you should have nothing to worry about, and be plenty warm by the end of the race. Now, there's the whole separate issue of how your body distributes blood when exercising so that you deliver oxygen to key muscles, but I'm sure Chuck and Kevin will discuss that ad nauseum some other day...