Move thumbnails to external hard drive

Hi

I've got LE9.2.8 on a RPi 3B+.

My media is all on an external hard drive mounted as an nfs through systemd, the mount is required before Kodi starts. The mount path is /var/media/RPi3BEHD.

My sd card gets a bit full for my liking, mostly due to Kodi's thumbnails, which I'd like to move to the external hard drive.

I found this link (https://kodi.wiki/view/Path_substitution) but I can't quite get the <to> part right, or at least after restarting Kodi, it can't find the thumbnails.

Here's what I'm using:

<advancedsettings>
    <pathsubstitution>
        <substitute>
            <from>special://profile/Thumbnails/</from>
            <to>nfs://var/media/RPi3BEHD/Configs/Kodi/userdata/Thumbnails/</to>
        </substitute>
    </pathsubstitution>
</advancedsettings>

I'm sure it's a simple fix but I'm stuck, TIA.

Damn, nobody?