When I first made the reservation, I was pretty conservative for campsites, I listed Chicken Spring Lake for night 1, SEKI-Rock Creek night 2, and SEKI-Other for night 3. Of course I ended up at Rock Creek on night 1 and above Guitar Lake on night 2. I didn't think to update it when I picked up the permit, I guess that information is useful if you go missing, they have an idea where to start looking. I was using a Garmin Inreach Mini to track my hike each day, so if anything happened the track would show my most recent location.
Also, I find looking at other's gear lists useful in preparation, so here is a partial list of the most important gear I brought:
Osprey Atmos 50 AG backpack
Tarptent Moment DW Tent
Sierra Designs Backcountry Quilt 700 (37F rated)
Sea to Summit Thermolite Reactor Fleece liner
NEMO Tensor Insulated Air Pad
Black Diamond FLZ Alpine Trekking Poles
Sea to Summit Ultra-Sil Dry Day Pack (for summit; very light and packs down to the size of a golf ball, but more than enough room for extra clothes and summit gear)
Black Diamond Storm Headlamp
UDAP No Fed Bear Cannister
MSR Trailshot Water Filter (for refilling on the trail)
MSR DromLite 4L Water Bag (I would fill this every night, drop in 4 aquatabs, and have all the water I needed the following morning for a quicker start)
Biffy Bags (easier to use than the ranger-provided bags)
Garmin Inreach Mini
Anker PowerCore 10000 (for recharging phone/watch/etc)
Garmin Fenix 5 GPS Watch
Kindle Paperwhite for reading
REI Weekender First Aid Kit with additional meds/bandages/etc of my choosing
Clothing:
La Sportiva Trango TRX Hiking Boots
Vivobarefoot Ultra III Watershoes (for camp shoes)
Kahtoola Microspikes
Darn Tough socks x2
ExOfficio Boxer Briefs x2
Kuhl Renegade Convertible Pants
Columbia PFG Terminal Tackle shirt (great hiking shirt)
Patagonia Tropic Comfort II Hooded Sunshirt
Merino Wool top and bottom base layers (not needed)
Patagonia Nano Puff Insulated Hoodie
Arc'teryx Beta SL Hybrid rain shell
Outdoor Research Foray rain pants
Outdoor Research Sun Runner Cap
Ascension Bay Glacier Sun Gloves
North Face Etip Gloves
Mountain Hardwear Dome Hat (great warm hat)
Mosquito Net (came in handy at Rock Creek)
I did not bring a stove, I ate my own trail mix recipe (lots of nuts, M&M's, granola, dried fruit), beef and bacon jerky, pop-tarts, fig newtons, clif bars, protein cookies, and Gu packets. This helped me save weight and pack space. My pack weight (with food but without water) was around 37 lbs at the start of the trip. Altitude did not affect my appetite, but the choice between camping a fourth night and dining on more trail mix vs. hiking a few more miles to the portal and having a big cheeseburger with fries made that last decision a bit easier.
