just an option:
Dan and I just did Langley last month. We got to Long Lake so early in the day, we just guzzled water there, filled up 3 quarts ( 1 for dinner, 2 breakfast/lunch next day) and spent the night at top of NAP. (We had spent 3 nights at Mammoth before, so had a little acclimatization). There are semi-sheltered camp areas at NAP. This gave us a tremendous headstart for Langley summit day. We kept going north after that into Miter Basin, but you would be returning south. A few pictures on my TR:
Miter Basin TR 
