Hi and thanks for answering 
I thought of changing the position of my custom ocean mesh at intervall so it follows my player. This makes it possible to have a mesh with lots of polys in the center and less the further away you get. Nanite would be great to use, because then I could have just a large high poly mesh, but it doesnt work with single layer water, as far as I know…
Im also considering making a custom PCG landscape generation around the player, but I have a feeling that creating this at runtime will be more performant than changing the position of the ocean mesh for example every second.
If I go for the change position option, I thought it might be more performant to have the mesh move as a gpu mesh particle instead of through blueprint!