The second response was correct. When you pick up the permit, ask then to change the exit date. So long as you have an overnight permit reserved, when you pick up the permit, you can designate as your exit date any day within 2 weeks of your entry. It does not matter what exit date you typed in when you initially reserved your permit. It is good for the rangers to have accurate info, so do tell them of your change in plans. The new, accurate, exit date will then be the one on your permit when it is actually issued at the station..
(And not relevant to your question, but no: even though LPL is not technically in the Whitney Zone, you DO need a Whitney Zone permit to spend the night there. You do not need one to day hike there.)
OP here. Thanks to all of those who chimed in. Without getting into specifics, I believe the basic answer to my question is; yes, I can, so long as I notify the station when I pick up my permits/canister/poop bag
that my exit date will be October, xx.
First night at Trail Crest, and my extra night at the camp right below Trail Crest (Outpost?).
