Narrow terrain editor brush

I am making a very narrow strip of terrain, about 250 units deep on Z and 10 - 15 units deeps on the X. The problem I'm running into is it seems Unity scales the brush to the terrain so if the terrain isn't a square, neither is the brush. This is making it very difficult to make smooth holes/hills in my terrain. Is there an option in Unity to disable terrain brush scaling? Thank you.