This is what works for me:
Like Shawn, I like vests. Down to about ten I wear a Kuiu merino wool top, KOM wool shirt, and a Hidden wolf insulated wool vest. More important, are the Kuiu merino wool beanie, neck scarf, and Hidden Wolf bomber hat. If the wind is above ten mph I add either a field jacket liner or the Kuiu Spindrift. For the lower half I use merino wool (1 or 2 depending on the wind) under a pair of KOM Bunwarmers. Anything works for boots in this temperature range with a toe warmer (on top of the toes) if there is a lot of room in the boots. When it gets down to around zero the insulated bibs and coat come out. Oh ya, the arm guard is a great idea, just do not cinch it too tight or you will have a cold bow hand. Try using an old wool sock that has lost is elasticity instead of the arm guard, it warmer and works. If you get high winds like Mark does in Livingston, you will need something that will block the wind.