Requirements

Cabins are permanent structures, providing a level of comfort includes:

• Queen size bed with two night tables and reading lamps
• Fully equipped bathroom with shower or bathtub
• Desk, chair
• Sealed or unsealed roof elevation mechanism
• Deck with two lawn chairs and a small table
• Climate control (if needed)

Here are some ideas to consider:

Tiny off-grid house by Room to Move

This family lives on a floating fortress of greenhouses in the middle of the ocean

https://www.diyncrafts.com/9000/home/build-self-sustaining-14×14-solar-cabin-2000