Once again me... I tested your work-around successfully. It's not really comfortable but works.
The main problem is that in my house not every level has the same wall height.
Here my step-by-step solution for every multi-level-user
:Basement : 90 cm
Ground level : 100 cm
1st floor : 250 cm
2nd floor : 250 cm
3rd floor/attic : 40-235cm
- Create a 500x200px texture for the desired 250cm wall
- Calculated the wall heights from every wall below current level (90+100+250)
- Calculated a factor (440/250=1,76)
- Add 1,76*500px to texture canvas
- New texture height is now 1380px
- Imported new texture and modified height to 440cm
- Finished.
