Full Moon Tonight-How to Best See Turtles at Las Baulas?

Do we need a private tour/guide to try to see leatherbacks on Playa Grande? On a website, I saw there's a $7 admission charge and a $7 guide charge, but I think that's through Las Baulas? Has anyone gone to Las Baulas this week and seen turtles? I'd really like to have this experience and somehow didn't realize until last night that it was a full moon, so I'd like to go there tonight. We have a rental car, just need to do what we can to maximize possibility of seeing them. Thanks for your help.