I would really throw the cross trainer out of the bathroom, maybe there is space in the HW room.
The HW room is the beer brewing kitchen. ;-) Apart from that, the cross trainer exists only in our imagination so far, and not every fantasy can be realized when building a house if financial resources are limited, as we may all have painfully experienced already. ;-)
Maybe it would be worth considering putting the thing in HIS room – as far as I know, you both have a hobby room each. Such a device really doesn't fit well in a bathroom. A trainer in his room also has the advantage that he can listen to music or run an app from the PC. Besides, it wouldn’t block the bathroom!!!
The thing doesn’t even exist yet ;-) see answer to barfly666.
But then you can’t paint over it!
But probably paint over it with glass paint? Or stick something on it or replace it again.
Wouldn’t it make sense to ask here first, before going on to the tile design, how to furnish the bathroom with the wishes “sauna, corner tub and co”? So a separate floor plan thread for the bathroom? I recommend that. And then you can decide on the tile walls afterwards :)
That is all already settled with the prefab house manufacturer and my husband and I are quite happy with it. For me, pictures and plants are the most important anyway, furthermore as little furniture as possible. And many, many windows. The upstairs bathroom has three windows; I think it will already be attractive for us because of that. I have often expressed the view that many windows, pictures and plants make almost every room beautiful, at least for me. (By the way, the sauna doesn’t exist yet either. ;-) )