Hi Maru, i tested your first setup, without sss, seems the simplest to start with for me. I attached a render with the result. I like the result very much, only there are some unrealistic things happening.
The problem with this setup is that the material becomes transparent because of the Refraction value. The bright dots on the walls are there because you see a bright sky behind the wall.
But actually the whole wall should have bright dots because of the light that falls onto the walls.
So in the render you should not be able to see the building in the distance. Only if you would put an object onto the wall or close to the wall, thus blocking the light, you would see a dark spot (check the reference i attached). Also the floor behind it should not become a dark spot on the wall, because it doesnt block the light.
Any thoughts?
Thanks for the help Maru!