If you are worried about writing to EEPROM too often you can use the update function to ensure that you are not stressing the memory if the actual value hasn't changed.
I don't have any experience with LittleFS but it seems like overkill if you are only dealing with a small amount of data in my...
Have you experimented with batching your writes to the file? I wonder what the impact of reducing the number of writes you are doing from 5x a second to maybe 1x every 2 seconds. This would only work if you are okay with losing a few readings in the case of a failure.
Rotating the logs is...