Question about MultiMeshInstance3D

For context, I am making a game that has a lot of grass, and I managed to implement chunking MultiMesh with frustum culling. Example:

https://reddit.com/link/1jf66gv/video/t8swjkz3appe1/player

Basically I have a "chunk manager" Node that loop through all the MultiMesh and turn their visibility off if (their distance between the player is greater than some number) or (they are outside the player FOV). The Multimesh loop all of its instance, then raycast down to place the grass.

While the MultiMesh that is culled is not rendered, it is still a node and is stored somewhere in memory. And if my world is relatively big, there would be some chunk of MultiMesh taking up memory even though the player is not even near it.

My question is is there more I could do beside turning off their visibility? Is there a way for me to queuefree the MultiMesh that is very far away, and load it back in smoothly? (maybe in a seperate thread if that is even possible since I need to raycast to place the grass)