[1.19.2] Keeping a specific chunk rendered no matter the client's chunk render distance

For some context, I am making a mod that recreates minecraft as a top-down strategy game (see: https://www.youtube.com/watch?v=2kL4vyjE2Mc). As part of this, I am implementing a "fog of war" effect where chunks outside of range of your base and mobs are greyed out and only render blocks as they appeared the last time you explored it with a mob. This currently works in my latest mod build but has the issue that when the chunk is unloaded and then reloaded (eg. by moving it out of your render chunk range and then back in), the blocks in the chunk are updated, which is not ideal.

If I can keep these unexplored chunks loaded indefinitely, then this issue would be fixed because the client would never update the chunk's blocks.

I'm not too concerned for performance issues here as I would only need to apply this indefinite loading to a select few chunks at a time (the ones containing other players' buildings).

I've tried cancelling the ChunkEvent.Unload event but it doesn't seem to do anything, and I'm not actually sure its related to rendering at all.