Get some army surplus wool pants to wear under your camo and a good wool sweater with windstopper to wear under your camo coat. The pants will probably be less than $20 and are very warm. You can wear whatever weight of long underwear under them you need. A neck gaiter will really help also. The sweater might run you close to $100 but is worth it. I have hunted late season for over 20 years and have found this combo to work great. Dont forget warm boots. If your feet get cold you are done.