Well I know all about cold tematures and hunting!! However it looks like I am of rare breed, since I much prefer pants to bibs. I guess it may stem from cold weather, as I find dropping the drawers to be less of a task when I just undo the belt and go...hehe (LMAO Mathews, happened to a buddy with covey' s one year) If it is really cold I wear 1-piece thermal under garments. However mostly I use 2 piece, I buy the tops larger so I can tuck into my bottoms to ensure they stay down. Always found the key to warmth is thin appropriate layers, consisting of thermal base and layers of wool & fleece (extra bonuses are less bulk and noise). Very important to keep your head, feet & hands warm. Fleece or wool caps or toques (as us canucks call them...eh!) work the best on top. Wool gloves and mitts, coupled with hot hands. Good thinsulate/gortex boots with liner socks(that wick moisture away from the skin) and quality wool socks. Important to drink water and eat foods that help generate heat, sucha s PBJ' s, Cereal or Granola Bars, etc. Refrain form taking that thermos of coffee or tea, as caffine makes you void more frequently...another important part of the heat loss scenario..voiding (P' ing) causes temperature loss, so you should try to limit the amount and types of beverages that cause you to do so (hence why they called it a " P shiver" ). If you need warm drink, than the best option is cup a soup style.
I never get cold while sitting in our late season and endure sub zero temps very regularily.

For those who find pants ride low, use suspenders on your pants. I have found the style for holding up tool belts to be excellent and you only need one pair as they just snap on and can be moved to other outfits.

BTW I don' t usually wear insulated pants or jackets either, I wear a fleece outfit that has wind stopper in them...very warm, thin, breathable and quiet. I find most insulated clothing does not breath well, traps & holds moisture close to the skin. (Of course they tend to be bulkier and some can get crunchy when the mercury drops up here(noise)

Thats my 2 cents and formula for beating cold weather, just another option.