Even at 140 cm length, you won’t be able to avoid splashes on the tiles. The “magic limit” for splash water is usually around 160-170 cm..
I was at the shell construction today with my plumber and we took another look at this situation. A 160 shower tray is doable (and he also finds it reasonable because of the splashes).
The thing is that for 160x120 you get only one shower tray – the Bette Floor Side. I don’t find it very suitable because it has the drain on the long side. So when you shower, the drain is to your left and not centered or behind you. I don’t find that aesthetically pleasing.
Has anyone ever had a shower tray custom-made? If that means about a 30% extra cost or so, I would rather do it with my preferred model, but if it costs twice or three times as much, then rather not. The plumber also advised against tiling the wet area again. He says nothing beats a shower tray if you want to be safe.
Maybe someone here has ordered or at least inquired about a custom-made tray and can contribute something.