Good to see you guys working with this setup.

RogueNZ, those profile shapes are possible. One way would be to warp the position of a simple shape shader that has a soft edge using a Get Altitude to determine how it shifts along X or Z through Y. And apply 3 variants with TGD I posted.

You would also need to shift the black and white points of that mask to give you the tapered profile. Colour Adjust does shift black and white points, but it does so statically, ie it doesn't change once set.

So looking at the base of your shape, lets say we have a circular SSS with a radius of 1000m with a Linear edge thickness of 1000m. This node will have a pure white spot in the centre and pure black at its edge, with a linear greyscale ramp from edge to centre.

What you can then do is use a Linear Step node to shift where black and white is within that circles ramp. Just as you can with a Colour Adjust shader. The difference being is the scalar inputs can be adjusted with further functions.

In this example you could use one Linear Step with Get Altitude as its input to create a black point at 0m altitude and white at 500m ramp, which you would multiply by a fraction (0.2 for example) so the output would be 0 to 0.2 and you can use this output to be the black point of another Linear Step which has the SSS as its input. This will shift the black point of the SSS ramp through altitude 0 to 500, from 0 to 0.2. Giving you that tapered shape at the base of your example.

The next step would be to do the same with the white point so that you have a constant falloff from edge to centre of the SSS disk. To do this, take the output of the Get Altitude/ Linear Step/ Muliply (0.2) you've just made and add another fraction (say 0.3) and plug that into Input 2 (the white point) of the Linear Step you used with the SSS input. This will give the profile 'solidity' in the centre and a feather edge of 0.3 all the way up through its altitude.

You can then use that output to Multiply a Density Fractal, or plug it into the DFs mask input, same thing.