Space can be smaller - along with the spa. Keep floor single level and try to keep spa flush to the floor - as well as window. Try to keep edges and walls smooth. Let the view speak in more volume than you could ever utter.
Bathroom Design, Alluring Classy Design Modern Bathroom Interior With Beautiful Lake View Floor To Ceiling Glass Bathroom Window And Luxury Bathtub On Floor Also Wall Mounted Sink: How to Design Bathroom Layout