Thanks for the ideas. I don’t think 1 would work, because I can essentially do the same thing in photoshop by just putting a crisp layer over the smoothed layer. What you get is a plateau that begins to drop off gradually and then slopes back up to the cliff height, and then drops back down. I can adjust the crisp cliff to be closer in or further out, but what I’m ultimately doing is just adjusting at what point in the gradual drop-off my crisp cliff sits.
For idea 2: I still haven’t done much with splines so I’m not sure; wouldn’t this involve manual editing of the terrain? My terrain is 2448100x2448100 cm2, and I just don’t have the time to do manual editing of that magnitude.