In the next update of Mosaico portrait monitors will have the layouts rotated by 90 degrees. In this way, for example, 1/3 layouts that are left/center/right in a landscape monitor will become top/center/bottom in portrait mode.
Custom layouts per monitor will follow shortly :)
Any update? I really need multiple monitor support. I connect my laptop to a 4K monitor. It’s not sensible to have the same window sizes on both when one is 4x the size of the other.
This is the only thing that keeps me from purchasing.