Is there a low-fi viewport mode?

I am trying to greybox my level in UE4 without bothering about the lighting. In lit mode everything is dark because I have no lights, but in unlit mode I can’t see any defining shades and everything blends together:

http://puu.sh/kUw0V/2adf3f5a1c.jpg

I can’t make out where one brush ends and another starts.

Is there a lo-fi shaded unlit viewport mode? For instance, this is a similar grey level in Hammer:

http://puu.sh/kUw8F/489b0da015.png