I want to stick with a three layer system. I have a light weight fleece, medium weight fleece, soft shell, raincoat, and down vest to choose from. I was thinking with a March 20th start date I could get away a dry fit t-shirt/light weight fleece/and raincoat. I also have a pair of North Face convertible pants...therefore could I get away without buying a base layer pant(Thermal underwear)? What does everyone think?