You can try Lone Pine Campground (elev. 5000). There are walk-ins...Heck, you may drive around or ask the camp host of any vacancies.
It can be very "warm" this time of year. There are bear boxes, pit toilets, and tap water. Also, Lone Pine Crekk flows next to the campground.
You may find vacant sites in WP due to no-shows. Ask the camp host.
