Chong Khneas is best avoided, the so called port authority monopolies the boats and many many customers have found their employees – the boat drivers & black uniformed guides too pushy; for example trying to push you into buying something dubious for an orphan. Refusing to buy often results in these people turning rude and even a bit scary, perhaps due to substance abuse. In recent years many children can be found begging.
I don’t usually discourage travelers from going to many places alone, but this is one, until Chong Khneas lift’s it’s game, there are many better places to see. If you still want to go let us take you and arrange the boat driver and guide in advance, perhaps combined with a visit to Kampong Phluk.