Django Admin: Using a custom widget for only one model field

After digging into the admin, model field and form field code, I believe the only way to carry out what I want is by creating a custom model field:

models.py

from django.db import models
from widgets import ApproveStopWidget

class ApproveStopModelField(models.DateTimeField):
    pass

class Stop(models.model):
    # Other fields
    approve_ts = ApproveStopModelField('Approve place', null=True, blank=True)

admin.py

from widgets import ApproveStopWidget
from models import ApproveStopModelField

class StopAdmin(admin.ModelAdmin):
    formfield_overrides = {
        ApproveStopModelField: {'widget': ApproveStopWidget }
    }

It gets the job done.

For the time being, I'll leave the question unanswered because I have the habit of missing the obvious. Perhaps some Django smartypants has a better solution.

Create a custom ModelForm for your ModelAdmin and add 'widgets' to its Meta class, like so:

class StopAdminForm(forms.ModelForm):
  class Meta:
    model = Stop
    widgets = {
      'field_name': ApproveStopWidget(),
    }
    fields = '__all__'

class StopAdmin(admin.ModelAdmin):
  form = StopAdminForm

Done!

Documentation for this is sort of non-intuitively placed in the ModelForm docs, without any mention to it given in the admin docs. See: Creating forms from models