Here you go:
https://drive.google.com/file/d/17L94YC0-OBGkHMIlf0L8GM8IEO59uYOr/view?usp=sharing
I unfortunately did not have time to clean it up, improve UX and test everything, but it should give you a good base:
The terrain is intentionally decimated to show that you don’t need regular topology to use it.
EDIT: Here’s a slight modification to make density mask work gradually, instead of sharp cutoff:
