When I interviewed Eddie Higgins, he spoke of what a thrill it was to be Hawkins' accompanist at the first Playboy jazz festival. Checking the transcript, Eddie mentions that he believes the music has been issued on four different LPs, fwiw. He also tells an amusing story about Hawkins showing up at the very last instant before they were to go on, and never acknowledged Eddie at all. He asked him what he wanted to play, and he grunted at him. He suggested some tunes, he grunted again. Then they went on.
IIRC there was one track on a 4 lp Playboy box I had in high school. Maybe that's what he was saying. Don't know of anything else from that gig. I think there was a Chet Baker track from that festival on the set too. Eddie's description of Hawk lines up with lots of other recollections - see Esmond Edward's story in the liners to the "On Broadway" disc.