Dimension with a constant underground biome and surface biome?

I'm trying to recreate the world generation of the Jupiter's moon Europa. It has a thick ice crust with an ocean underneath.
I've taken inspiration from the The Expansion datapack which adds this moon, and tried to change the underground ocean to use Alex's Caves deep ocean cave. However it only generates small parts of this biome instead of a complete underground single biome and multiple above ground plains and mountain biomes.
Any ideas of how this could be done?
Would I need to remove some of the noise routers in the dimension to stop stone from generating between underground oceans?