Who knows when Neptune will have a magnetic mount for the new LLS so, off to Tinkercad we go. Here's an STL that you can tweak as you like. This mount reuses one of the magnetic mounts from an optical sensor. Like me, you may have an available optical sensor now that you have an LLS. Simply unscrew the clip from the magnet then superglue (or whatever) the wet side of the magnet into the back hole of the mount. Pics are of first mock-up and fit, printing a more pretty one as I write.
Neptune Apex LLS Mag Mount 1 by jmhinsd
This was designed to hold the new Neptune Apex LLS and it utilizes the magnetic mount used for Apex optical sensors.This object was made in Tinkercad. Edit it online https://www.tinkercad.com/things/hqXOiftZYmo
www.thingiverse.com