I doubt anyone there is going to want to handle money/membership stuff. Just send in the membership form and dues like you normally would. Doesn't even have to be before Saturday. No one is going to be checking memberships cards at the put in. We don't get crazy about that kind of stuff. If you want to come out for a few paddles and see what RICKA is all about, feel free. If you enjoy it and want to do more trips, it would be nice if you became a member.
Just a note though, I'm not sure what your experience level is but at normal water levels this trip does have a few short and fairly easy Class II rapdis. The water level will probably be low so in addition to a few rapids, there could be lots of scraping and maybe even some walking. If you want more info about the run just shoot me an email.