Ah -- tough call -- I use a pair of UnderArmour tights "Cold Gear" with shorts over and a pair of jockey underwear underneath. And I liberally apply body glide to all the rub-points.
I also have used a pair of over-pants - just once - but I was happy with them. Depends a lot on the wind.
It looks to be a little chilly on race day! I don't think we'll see 40 degrees until beer time. Could be around freezing at the start. I've never worn tights, any recommendations?