And arriving by bus is one of the ways you can legally stay in the backpacker camp without having that permit -- it's in the compendium, which is on the Yosemite website, that walking, biking or riding a bus into the park allows you a space in the backpacker camp. Rangers sometimes don't understand that, so go print a copy of the superintendent's compendium to take with you.
Thank you, AT! This is really helpful. I found the compendium. Here's what it says:
"Backpacker camps are intended for use by visitors in possession of an overnight Wilderness
Permit or for visitors arriving in the park by foot, bicycle, or bus.Wilderness permit holders
may stay in a backpacker camp the night prior to departure and the night after returning from
each overnightWilderness trip."
"Users arriving in the park by foot, bicycle, or bus may stay in each backpacker camp for a
limit of one night."
If I understand it correctly, that gives me two nights at the backpacker camp. Here's the link to the compendium if anyone needs it:
https://www.nps.gov/yose/learn/manageme ... endium.pdf