How does it work if all camping sites are taken are you able to have fires in areas that arent designated camp sites?
I'd say find a nice quiet spot off trail and practice the LNT techniques. Actually, I absolutely refuse to camp at a designated site and even avoid state parks as much as possible. Too much traffic, usually trash all over, beaten down muddy earth, people deficating all over the place. Not for me.
Of course you can have small fire. The fire rings apply for established sites only