Ultralight base layers and hiking pants recommendations

I have a set of merino wool from Amazon but they are heavier than everything else I’m carrying.

Looking for something light that is good for warmth. AT start date 4/12. Weather could go either way, I despise the cold.

Have a 10 degree down quilt, EE torrid, alpha 90 hoodie, REI gloves, beanie, REI sun shirt.

Base layers don’t have to be merino, just warm and light/versatile.

Pants will be new for me I usually wear leggings but going to give pants a try, must be extremely stretchy, I want no resistance in any plane of movement, also want something that can adjust to weight loss easily.