I suggest you include PSKReporter
in your demo, if you will have a good Internet connection. It's very visual, like WSPR but even more interactive as you can demonstrate it during QSOs. See http://pskreporter.info/pskmap.html
and the instructions one level up at http://pskreporter.info K8CMO
you may want to make use of PSKReporter
as well, to ensure you're being heard and to determine if you're hearing stations you should hear. PSK31 is very active night or day.
73 de Joe K6ATZ