Help with bathroom design for existing properties

The measurements are with tiles, there are still some on them. In the main bathroom, there is even a wooden paneling on the slope.

Would a roof window help???

The shower under the slope has the disadvantage that the shower enclosure also becomes more expensive. ;-))

For the bathtub in the guest bathroom, placing it crosswise was also suggested to me in the studio. Unfortunately, it is then only a 1.60 bathtub and the seating area is only 1.10. I am 1.87 tall. ;-(( I did not like that very much. That would really only be comfortable for the wife and children.