Going on an eight week trip to the mountains soon with daytime highs ranging between 18C (70F) and -10C (10F) with potentially serious snowfall. I will make about 30k or 20 miles a day.

I'm definitely going to bring the following:
Sun/Fleecehoodie (KUIU Peloton97 - 200g)
wind jacket (200g nylon)
rain jacket (400g 3 layer)
down jacket (400g)


Which merino baselayers would you bring considering that weight is a serious concern?
- T-Shirt 150g/m
- Longsleeve 150g/m
- Longsleeve T-Zip 200g/m
- Longsleeve T-Zip 250g/m

Will I be ok with just the T-Shirt or should I bring more?