55 degrees on race day - what to wear for bike

I'm racing a HILLY first time Olympic tomorrow and weather calls for 55 degrees!! eek! and sunny.  I've only race 3 other tris and all were warm. I usually race in tri shorts and Nike swim bikini top under my wetsuit, if I even wear a wetsuit.   I throw on a tank with my number for the run but bike in the bikini top.  I'm trying to win this one so transition needs to stay fast.

I have toe covers on my shoes and will put on arm warmers and a beanie on in T1... but still bike with a wet bikini top.  I figure my bare skin dries faster than wearing a full tri top in the swim and letting it air dry. 

Any female experience with mid 50 temps in bikinis?  Thanks! Much appreciated!