I wear three layers. A skin-like base, a thin merino wool sweater (this is thin like a tee shirt thin) and a wool jac-shirt. In my pack (you need a small pack) is a packable down vest. These are meant as an under layer, pack into a small ball, are very light yet insulate very well. In addition, I carry a stretch vest. This is wind block type fabric (polartec?) that does not rely on a liner which would be heavy. Rather relys on its tight weave. Also quite thin and light, but does a great job over the down vest, or alone.
I wear thin wool pants and if it gets cold put on a thin pair of long johns under them.
Thin wool is very adaptable. Most guys wear wool that is pretty thick. I like the thin stuff because it does not over-heat you like the thicker does when its warm or you are hiking in. I can take off the jac-shirt, or the sweater, or both. Then put on the thin vest, or the down vest (or both) or everything if its cold. Thus I can stand temps from the upper 20's into the lower 70's with this system.
A small pack will make this whole clothing problem a lot easier to solve.
Joshua.