No there’s no dry camping in the official sites. However, if the park is full, they may let you stay in overflow on a night by night basis. It’s not a great situation however, because they are inconsistent in how they administer overflow. They also make you park 3 feet way from the next rig, and if their generator is running, there’s no escaping the noise or fumes. Plus it’s $20, with no restroom nearby.
I believe that only in group camping area. You can call the ranger station directly at the park and ask if you can’t find the information on their website.
Last year the group camping area was utilized as an overflow area when it was not reserved. I can’t say if they’re doing that again this year. I agree it pays to call.