Having been to Nam Sai many times, I went around mid April, but when one of the sailors on security saw a farang face it was a no go.
So, a couple of days later, I by-passed the security check, and went through Samaesan, right to the car park at Na. Sai, only to be not allowed on the transit songtiews to the beach.
I'm sure it's because they've inflated the prices to Hat Nam Rong...