Of course you could camp on the passes, you had all the water up there that you could ever want, right?
I recall very clearly arriving at the top of white pass, and among the steep talus ridge was a perfectly flat and level rock about the size of a queen bed, and I thought "I've got to come back here just so I can bivy on that deck."
I always slept high, but not on the passes. I think for the moment I will stick to roper's tact, and keep the discussion of campsites vague.
High in humphreys basin, far above treeline, I got shut down by an electrical storm which stopped me from getting over puppet pass. I pitched here to ride it out, at some lakes around 11,300'. It was one of those tarp-education days, just add 40 knot winds, marble-size hail, and lightning strikes to this picture:
As usual, the next day I got some miles in before sunrise, hitting puppet pass at dawn. It was the only time I saw that wierd fog clinging to the peaks.