I did pretty much exactly as @Chosker described above. I set up the landscape/rvt/vhm as normal, and then in the main section of landscape material I use WPO to displace the vertex positions according to a mask generated by a Render Target.
If you’re getting slow updates I can only assume you’re trying to apply the render target to the runtime virtual texture output, which is not what you want.
For what its worth, I used that exact tutorial for the snow trails as well, and I don’t recall doing anything special.