I'd second the Cabela's Synthetic Down jacket. I've used it for a few years now and I have questions about the durability of the outer shell fabric, but I only use it when I'm sitting and glassing when its cold, so it serves my purposes. I think that if I assume you're wearing other layers, then this jacket would work. It is definitely not bulky and is actually relatively thin. If you were only wearing a light shirt and then this jacket over it, it might not be enough for 10F, but if you have on a base layer and reasonably warm shirt, I would think this would do it.
