Thanks for the great responses. A bit of follow up:
1. We are arriving on the West Coast (coming from NC)early Saturday morning and going straight to Mammoth Mountain. We plan to take the gondola up to 11,000 and spend most of the afternoon there and then sleep at altitude in the lodge Saturday night. I did the same thing last year and had no AMS symptoms the entire time. I also do have Diamox from last year, though I ultimately didn't use it then. We did have one extra night sleeping at altitude in Mammoth last year, so I am at least considering use of the Diamox this year.
2. I didn't realize we were allowed to camp near Lone Pine Lake outside the zone and I wasn't sure about even setting up a late camp at say Outpost Camp (say, right after midnight). Knowing both of those options are OK, gives us some flexibility.
3. Glad to hear there is some real hope at getting an earlier entry permit. The two other members of our party will be arriving in the area on Friday and can seek the permit for Sunday entry. If we get it, then great and we free up Monday permits. If not, we can use the option of camping at LPL or late setup at Outpost Camp.
4. Never seriously considered just turning it into a day hike, but that could possibly work, too, in a pinch. Having done this last year, the idea of the lighter pack the entire 22 miles definitely has it's appeal.
Thanks again for the tips. I feel much better about our options now. Any other thoughts welcome.
