Thank you for the amazing challenge. For your better understanding I created a virtual tour of your room to get the feeling of the space better.
Anyway, for your design I created a functional layout to make use of space and give every inch of it a functionality. In the low ceiling part I put the activities which are done in lying down position such as sleeping and using the Jacuzzi to make use of height for other functions.
Furthermore, the bathroom is divided into two sections shower and bath. In my design I used smart glass that can be transparent or opaque when you need privacy. The shower is located between bathroom and Jacuzzi to be use by both. The toilet is also functional and have double sink for hosting couples.
Hope you enjoy