在w中访问OneToOne相关模型的字段

How to get another fields of related model inside ModelAdmin panels List? Tried this: 'user__first_name', doesn't work. It seems that its not possible out of the box, but maybe have some one already done this? There are my models, User is just regular django.auth User model and it has first_name by default.

# models.py
class Customer(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE, related_name='customers')
    org_title = models.CharField(max_length=500, default='', blank=True)

# wagtail_hooks.py
class CustomerAdmin(ModelAdmin):
    model = Customer
    menu_label = 'Customer'
    menu_icon = 'pilcrow'
    menu_order = 200
    add_to_settings_menu = False
    exclude_from_explorer = False
    list_display = ('user', 'org_title')
    list_filter = ('user', 'org_title')
    search_fields = ('user', 'org_title')
    panels = [
        FieldPanel('user__first_name'),
        FieldPanel('org_title')
    ]