Best layering system for the Sierras?

I’m really confused as to what I’ll need for my 600 mile Sierra route.

What I’m currently bringing:

Worn:
\- sun hoodie
\- shorts
\- shoes, socks & boxers
\- hat

Packed:
\- rain jacket
\- synthetic puffy
\- windbreaker jacket
\- wind bottoms

Everyone always mentions Alpha. Would this replace the synthetic puffy, or should I bring it as another layer? Or should I bring the alpha and leave the puffy at home? 🤷🏻‍♂️

I know the weight isn’t much but I I dislike the complexity