Tesselation on terrain

Been googling for a couple hours now trying to figure out how to add height maps to my terrain textures using tessellation. So far, no luck. The problem I keep running into is Unity saying it can't use terrain that relies on tangent geometry. Is there any way around this? I'd really like to be able to add this additional detail to my terrains.
As a side note. Is there absolutely any way possible of achieving more than 4 splats? I'd like to have some variations of my textures with the smoothness changed so I can paint wetness.
As a side note. Is there absolutely any way possible of achieving more than 4 splats? I'd like to have some variations of my textures with the smoothness changed so I can paint wetness.