I have done something similar by casting ray vertically down one step ahead of player. You record where will the ray hit ground and what will be the inclination.
Now if the dH (difference of heights) at hitpoint is less than vertical step limit AND the inclination there is small (i.e. not steep) go ahead and move.
If the dH is bigger than vertical step you have hit steep rise.
If the dH is smaller but the inclination is high you have potential steep rise and have to test two steps ahead.