So do you know if it is possible to move /opt/retropie/configs to the SSD?
Not without a reinstall and without re-formatting the SSD to ext4.
If you wish to keep the artwork on the SSD, you'd have to eithercopy the downloaded_images folder on the SSD and then make a symlink from $HOME/.emulationstation to it. When moving the SSD to a new system, you'd have to re-create the symlink there, so the downloaded_images points to the SSD folder. move the downloaded_images folder on the SSD and adjust the paths in each gamelist.xml file to point to the new location. Useful if you don't want to add new games and/or scrape again.