I work in old measurements because that's what I'm used to.  Don't like metric!  But that doesn't really matter because you can always roughly convert 1 yard to 1 metre.

I'm using one of the old Vue trees in my render - the Summer Cherry. Everyone has that

You don't really need to use a procedural terrain unless you're going to be seeing a lot of details.  I t just takes up memory.  I just have a standard terrain tilted toward the camera (shown in earlier screenshot).  The density of the trees plus all the mist and cloud covers it all so the terrain itself isn't visible.

If it'll help, when the render is done I'll simplify the scene and send it to you so you can take it apart and see where everything goes.  I'll have to replace the rocks with simple spheres but I can leave the ones that I rendered separately and put on alphaplanes to save my memory.

I will also have to modify the material ecosystems I used for the rocks as the base material was a purchased item, not one of my own but I'll choose a standard Vue one that's acceptable.

Let me know if you'd like the file and site mail me with your email address if you do

Gill