I think I have to translate my "tips and tricks for Vue" in English language. For the momenet they only exists in french and german.

In the image above, I created 1 terrain which I have resized and flattened and pushed it completely under the ground. It doesn't disturb at all in the image and you can make the grid invisible or not whenever you want.

In my previous post I created 2 terrains, each one colored differntly and placed them shifted under the ground. I also created a vertical terrain, resized it to fit in the views and put it very very far away. Here again, you can make them invisible or not by just a click.