I had the 4L water tank for desert portions where there won't be many water supply points. I will probably put the camp suds in a BPL container, which would mean that I'd take a lot less of it. Any Dr. Bronners VS Camp Suds insight? I can see ditching the umbrella when not in harsh sunlight or heavy rain.
Would probably rent a bear can for the JMT and use an Ursack in other problem areas. Funny you should say something about the trash bag liner, I did that in the military. How much do they weigh?
I've hiked quite a bit without even using a compass, I'm pretty good at terrain association (military land nav training beaten into my head). Having the "real" compass is just sort of a comfort thing. I'm sure 95% of the time dead reckoning covers it.
The towel is for bathing, drying off after rain, etc.
I may just apply permethrin to problem areas rather than bringing Deet.
The underquilt is 3/4 length, which means I'd have to place my pack, a rain jacket, or something else under my legs to keep them warm without a pad. The pad would also be used for sitting/resting. It also adds a nice bit of insulation for 5oz. And yes, for a situation where I couldn't find a tree (not likely) *or* more likely would be being in an area where I'd be worried about deadfalls.
I dehydrate and prepare my own meals in vacuum sealed bags, I can eat out of these.
I really appreciate the questions, you have me moving in the right direction now! :)