Planning guest bathroom, need your tips

And, one could consider placing the toilet diagonally at the top right corner.

I would do that too or rather, we have done it. It provides more legroom on the toilet.

You have 130 cm room depth, a 20 cm partition should be enough and the toilet about 52-55 cm. That leaves 55 cm. And, one could consider placing the toilet diagonally in the top right corner. And check whether the partition really needs to be 20 cm deep.

I also like the idea, I have drawn it in.

However, if the shaft remains at the top, it all becomes too tight for me. I have now placed the shaft to the right. The distance from the toilet to the opposite wall is about 60 cm, the washbasin to the opposite wall about 55 cm.

I think it shouldn't be narrower, possibly increase the width from 131 cm to 141 cm. Then you would have 70 cm and 65 cm distance respectively.

You could also use a smaller sink in the guest bathroom.

Yes, just don't make the sink so huge. In the bathroom, you only want to wash your hands. A small hand washbasin is sufficient for that. I would place the toilet against the upper wall of the plan and then put a small washbasin in the corner.

If you tilt the [Toibecken], a usable depth of the space of 1.20 m is sufficient.

I have also started another thread for the planning of the guest WC.

I would also be grateful for your valuable feedback there :)

You might want to post everything about the house sometime. Maybe it would be sensible, for example, to have the front door hinged differently? ;)