I'll tell you what I have been doing as a section hiker, although I know this may be open to criticism. Understand that I have been hiking the CA desert sections in May and June, the Sierra and north in August usually.
I layer a merino wool shirt, with a fleece layer and then a wind jacket and wind pants as needed. So far over 1000 plus miles in I have experienced just one minute of hail, and zero rain. I have not regretted not carrying a waterproof shell. I do carry an umbrella which I could utilize if needed. The umbrella has been vital for sun protection. In the event of a serious cold weather downpour my plan would be to hole-up. I can set up my tarp in minutes. I carry plenty of down to keep me warm when I camp.
To tell you the truth I've spent most days of my hikes wishing it would rain, or at least cloud up. I love the hiking on the CA PCT, but the sun has been just killing me.
I am sure I will take a different approach by the time I get to OR and WA, but for now, given as a section hiker I have control over when I do each section, this is what is working for me.