Yes, but check online to make sure campsites are available during popular dates. If you drive up for the day there is a sign showing the fees, which sites are not reserved and a self pay station. If there is no staff or host use the self pay. if you do not have cash fill out the envelope and write your cell # so they can call you to take payment by card.
Yes, but check at the front which places are reserved.
Yes you can go without a reservation. As far as signs for fees are on the website or Google Campgrounds in Idylwild has most general info here. I know it worked on an honor system where if no one is attending the gate you can choose a site and pay with provided envelopes. Usually there is a camp host for this type of thing to steer you in the right direction but when we camped there last month there was no host. I hope I helped you with most of your questions and happy camping 🙂
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