Layering of tech shirts

EricNCSU

I am running a race that starts at Midnight tonight and I'm trying to figure out what I am going to wear. It's not going to be bitter cold, but it's going to be 40-42 degrees and dropping (the 5AM low will be 36). I have underarmour leggings and shorts for my lower half and this has worked well for my outdoor training runs, but I tend to still get cold with only my long sleeve tech shirt on. If I wear my shortsleeve tech shirt under it, am I going to lose the benefits of the breathability, sweat wicking etc? I also wonder if I layered with a non-tech shirt if I would lose the benefits as well... such as short sleeved tech shirt, with long sleeved cotton tshirt on top. I dont have a zip up type coat that I could wear, zipped up while we are standing around, and then unzip it while running etc.

I want to stay warm, but at the same time I tend to get over heated so I'm looking for a delicate balance of not freezing and not dying of heat exhaustion.

Any advice? Thanks!