Trickplay and Chapter Images storage location.

[Nariagari]

If you run a docker container you should be able to change the location:
    volumes:
      - /newtrickplaylocation: /config/metadata/library

The problem with this solution is that all the metadata would be stored on an external device.
Small data like Pictures of Actors and Movie Wallpapers are small enough to be stored on the smaller but faster SSD. Also, they get viewed more regularly.
But Trickplay is only used if you watch something, and it accumulates to much more data than the other metadata.