Remember Chef, your number one objective is to stay dry in the first place. Don't put on so much clothing that you start sweating. You'll regret it. Keep the on bike clothing to a minimum and you'll love the trip immensely. Put on layer after layer and you'll hate yourself for it in the long run. You don't have to dry anything out that doesn't get wet. Sure it will get damp. Heck the first half of today I was totally dry and the temps were in the upper 20s to lower 30s and I only had a long sleeve cotton tshirt and a wind jacket where the half length zipper was not zipped up. Let the heat escape and it won't build up to the point where you start sweating. Your objective is to feel comfortable...not warm. If you feel like you do right now could you keep riding for the next 3, 4, 5 heck even 6 hours. Ask yourself that question. If you are sweating and something happens you'll start to cool down very fast, sweat is designed to cool the body down, not to keep it warm. Avoid the sweat and you'll ride all day without any problems.
I will agree with Machka on having the extra layers for evening/overnight. Use the clothing both to keep you warm and to give you something to...heck already have on coming morning so you don't have to change clothes in the AM. Remember as a normal rule that is when the temps are normally the lowest.