Good place to do a private health cleanse around Krabi?

Does anyone have a suggestion for a location or a specific resort/hotel in the Krabi area that would be conducive for a private health cleanse and retreat?

A couple of friends of mine from Holland would like to find a place near the sea where they can spend a week on a green smoothie and raw diet.

They know how to do a cleanse so they don't need or want any assistance or planned program. They just want to find an ideal location, preferably without the crowds. They have a decent budget to spend, between 5K-10K baht per day and they will need two rooms or bungalows.

Any suggestions, recommendations or creative ideas?