Dan,
I am impressed with your advanced planning and attention to detail.
The new Conduits do well with self-infating mattresses. The pad sleeve has been replaced with a couple of straps and Brian now recommends using a 3/4 length self-inflator. Since you could get down into the 20Fs, an ultra-thin closed cell pad might be warranted in addition to an air unit. My Prolite 4 small is a perfect size for this pack. I have a BMW 10oz mattress that is still in the box, but I am sure it is going to work well in the ULA pack. Sounds like the new Therarest is still VaporWear, and it weighs 4oz more than the BMW.
Base layers and pants: My 30 x 32 REI Mistral soft shell pants weigh 13.3 oz, so I would ditch the REI Saharas and maybe bring an Ultralight base layer. In 50F and under, the Mistrals are not too warm, and they do breath somewhat and are water repellant. REI has them on sale for $99. When high temps start getting into the 60s and above, then the Mistrals stay at home with the wife.
A 2L platypus or Nalgene soft water bottle weighs around 1 oz or less? versus your 1.8L bladder @ 3.5 oz.
You say you sleep warm… you could use a much lighter bag, but that is a major investment!
I would skip the underwear… savings of 3.5oz, of course this is a personal preference.,, but I would not skip TP!!
I would probably go with my Montbell wind shirt @ 2.9 oz and my Montbell Extremely Light Down Jacket at 5.7 oz… saving around 7oz on your REI jacket — although the Thermawrap is a good option too.
I know you are stuck with the tent, but I would go with my GoLite tarp/poncho and MLD Soul Bivy or just my 6 Moons Wild Oasis. The tarp/poncho @ 10oz plus stakes handles my rain gear/pack cover and shelter. The bivy @ 8.8oz is insurance with a tarp. I have used the Wild Oasis down to 20F and lots of snow/rain with good results… and it is under a pound.
For this time of year, I would ditch the hat and use the bandana and/or fleece cap for the head. Where I live, hats are a must with summer temps sometimes exceeding 120F and I wear one almost all the time, but not necessary on this trip… however I almost never leave home without it.
A Classic model Swiss Army knife weights about an ounce less than your knife.
Since I am a new member… no one knows me, so assume I know nothing :)
I did upload my master gear list a few days ago. It shows the stuff I usually use in the high desert this time of year when the lows might get to 30F (although a month ago I hit lots of snow and 20F). I can even pare the list further, but as an aold fart pushing 60 I do have a few indulgences. Since it is a master list, you might want to cruise through it — just to look at weights of different items. I find that it is a pain in the butt to search all kinds of Websites for weights. Most of the items I weighed on my postal scale, but a few are published weights… as my wife whines when I am "playing with my toys" at night.
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Lastly, a $1 investment in a Lottery Ticket has a 1 in 200,000,000 chance of financing your upgrades and trip.