From reading your description, I'm thinking that you believe that the 17' will allow twin beds and at the same time, a dinette to sit at.
We own the 17' Casita
Liberty that has the king or twin beds. We use the twin beds and love them. However, when the twin beds are up, there is no dinette. The twin beds take up the entire back area of the 17'... The same as when we used the king bed.. No place to sit.
You could put a table up on a post, as we do, between the two twin beds. We put the table up between the two beds to eat or play games with friends, but it comes down when we aren't using it and when we sleep.
I know there is more height in the 17' and the floor is level, no raised portion in the back.