Thank you guys for all the suggestions. Manfred, your inputs are direct and on point.
I'm in the market for a lightweight wind shirt (too bad the Stoic Wraith Shell is no longer in stock), down jacket w hood, down quilt and a great down beanie. I've hike with foam pad in the past, but it's too bulky. I'm debating between Z-lite vs neoair xlite.
Matthew, you are on point about physical reconditioning. Did my first half marathon last month, and currently training for a full marathon next march. But all that running is nothing compared to hiking with 25+ lbs on your back for days. Hopefully, after the full marathon, I will be able to focus more on weight training for back, legs and core.
M B, 12 days and 100 miles is also one of my concerns. I just randomly follow past hikers who post their itinerary on the blog and 12 days seem about right at Muir Trail Ranch. Plus, I don't know much about my fellow friends and their current backpacking stats (eg base weight, quality gears). We all love to run, and in fairly good shape since most of them have finished either a 1/2 and/or a full marathon. If everyone could go as light as possible then we can really get going fast. Perhaps, camping off trails would fill in some of those down time, and a side trip to half dome. I really don't know any better way to guesstimate average mileperday rate.
My personal reason to go lightest is because I want to haul a full-frame DSLR, tripod, and 1 lens, of course all this would be a shared weight.