I'm looking at purchasing at least a jacket/parka. What would everybody recommend for bowhunting? I know their stuff is custom fitted, but what's your experience with being able to layer underneath? Do you buy a size up or is their stuff built with a little slack. Also, what materials for insulation and outer shell? Again, I strictly bowhunt through November. No gun hunting or late season bowhunting when it's snowman weather. Thanks.