Django: Admin list_filter getting too long
You could try using dal_admin_filters its Django autocomplete light filters for django admin
https://pypi.org/project/dal_admin_filters/
Looks like it may be what you're looking for
While dal_admin_filters seems to work it hasn't been updated in a while (2017) and predates the introduction of auto-complete fields in Django 2.0.
If I was you I'd try my luck at implementing my own SimpleListFilter subclass based on the new auto-complete endpoints exposed in Django 2.0 and dal_admin_filters implementation.