Oops! Don't quote me on the lottery for the North Fork walk-ins.
I think I may have assumed too much. Now that I think about it, I once got to the Lee Vining ranger station, since it is closest on my route over the Sierra, at 11 AM, and got two walk-in permits for the next day on the North Fork LPC trail.
But that may not be possible now, since it is within the Whitney Zone, and W.Z. permits are supposed to be available only at the Visitor Center s. of Lone Pine.
I should probably inquire about the current North Fork procedure.