You can and WILL crush this mountain! You've got this. I'd say wear as little as you're willing to tolerate. Then any layers you add on top just be sure they're all things you'd be willing to toss mid-race. Another one of my top rules on race day:
Whatever you decide to do is the right decision. Don't second guess during the race because that only breeds negative thoughts. Wait until after the race is over to evaluate the decisions you made and dissect all the little bits and pieces. So whatever you choose to wear is the perfect choice.
I advise that you do a little warm-up before the race (again no earlier than 60 min and no sooner than 15 min to start). BUT with the temps where they are, be extra mindful of not sweating during the WU. Sweating during the WU and then stopping for the pre-race stuff can really cause the chills. So if it comes down to being too warm to WU without causing sweating, then skip the WU. Just take the first few miles a touch easier then desired to let your body WU then instead.
Go get'em!