Mt Whitney Zone Forums Thread Like Summary - First-come, First-served Campsites

I've only ever reserved campsites in Lone Pine Campground and Whitney Portal Campground ahead of time. I'm curious if anyone has any experience with the campsites that are first-come, first-served? Do you literally just show up, and if it's empty, take it? Is there a specific time (like a check-in/check-out time) that you have to follow? I'm guessing there must be some sort of payment box somewhere? Can you stay in that spot for multiple days?

Any info that anyone has is much appreciated. Thanks!

There is usually an official checkout time, like a hotel. After that time, you can just show up and take it. If the previous campers leave early, you should be able to claim it as soon as they leave. You normally fill out an envelope, put your money in it, put in some kind of box, and attach a “receipt” near your campsite to show that the campsite is occupied and that you paid. Campgrounds usually limit you to staying 7 or 14 consecutive days.

retrofan, if you go and cannot find a first-come, first-served site, consider the "ravine campground", a tucked-away walk-in set of sites, downhill from the overflow parking lot. The regular backpacker walk-in sites are closed due to the recent earthquake and rockfall damage, and I'm not sure if it will reopen this season. So the ravine campground may see a lot more use. But it's worth checking out.

Here's a link:   Sleeping in your car at Whitney Portal

This map/picture is shown in that thread: