Quote:
Permit for July 12 but I'm now meant to be in Vegas that night. .... or I try to get an unused permit for July 9,10 or 11.

B777: Since July 11 is a Monday, it is quite likely there will be plenty of no-show/cancellations available for you to pick up. Just be at the Visitor Center at 2 PM on July 10.

Last year's Unused Permits numbers show there were always day hike permits available on every Monday. Sundays were mostly ok, too.