We have been staying in the area for a few days and can provide the following information.
Goon and Gib restaurant on White Sandy beach has been open since 1 August and will stay open into the evenings if they have customers.
Khun Dang restaurant is open on the beach next to the Mai Kaho Lak. Not sure about Elicious or Mama and Mr Leks, it was poring with rain when we rode past.
All other beach restaurants closed including the Rimlay.
A good restaurant open on the road running down from the highway to the Kantary, Krua Rim Trung (spelling). Good value about 1km from the Kantary.