Terrain Tool - Only square splatmaps?

Deadly Nightshade

A colleague of mine has been playing around with the terrain tool in Unity recently. One thing that we don´t seem to get a hang on is how to change the dimensions of the splatmap. Changing the dimensions of the terrain itself to say a 2:1 or 4:1 ratio only stretches the splatmap (and all brushes). How can this be edited so that the splatmap isn´t 1:1?

EDIT: Seems impossible:
http://answers.unity3d.com/questions/681396/none-square-shaped-terrain-gives-squashes-terrain.html

Any ideas whenever this might change in a future version of Unity???