You can use an anti-clogging agent, such as Dupranol, to help keep the windway open, and/or, the player can (gross!) suck back frequently, during rests, to clear things up. If not playing with other instruments, the lowering of pitch as the recorder cools will probably not be noticed by the audience. Keep the piece short, and in the midrange of the instrument. Serve everyone some wine first, if possible. Good luck!
MD