What about running a Scalar Generator into the Radial Gradient (with diamond or cone setting) and then you would be able to essentially go from a vertical slope to a flat horizontal slope in the scalar range of 0-1.
Maybe could convert the slope to want to radians and then get the 0-1 scalar value you need to plug into the Scalar Generator node.
Hummm, am I thinking about this correctly? For a 5% grade:
grade / 100 * 90 = degrees
5 / 100 * 90 = 4.5 degrees
and also
grade / 100 * Pi / 2 = radians
5 / 100 * 3.14159 / 2 = .0785 radians
Take the cosine of the radian angle to get the scalar value needed to put into the Scalar Generator node:
cos(radians) = scalar value
cos(.0785) = .99692
Been too long since I tried to do this stuff. :roll: