By late next month, the southern California section will be both very hot and, in this year of horrendous drought, very dry. The water caches will no longer be maintained and most natural sources will have dried up. Are you already in condition to do 30 mile days with all the water you'll have to carry?

There is often plenty of snow in the high Cascades of northern Washington by early October. Some years sooner, some years later, but that's a good average. Many years, people who try to stretch the season into October have been stopped in the middle of Washington.

With a late June start, had you considered going southbound instead (that's about as early as you can start in the North Cascades)?

Your list mostly looks pretty good to me. I'd definitely add a lightweight base layer top and bottoms. Frost and snow can happen any time of year at high altitude, even in midsummer, and certainly by September. While in motion on cool days your shirtsleeves may be too cool but the Nanopuff will be far too warm--an added lightweight baselayer top is (for me) often just right. I'd also be concerned if your quilt and pad (and your balaclava) won't take you down to 20 degrees F.