I really suggest you check out some of the Thai house and garden magazines, the ones sold in the newsagents, not the fancy coffee table books.
They have some nice places in there that aren't overdone with expensive features and furniture. I'm sure you'll find some good ideas. One I have at home has a place very similar to your sketch. The underneath part is brick paved with a garden surrounding.
I would also consider a simple kitchen downstairs, doesn't need to be fancy, just a gas cooker, sink and one of those rat/insect proof cabinets.