Select item in Django admin inline with radio buttons

Question

Here's part of my models.py:

class Person(models.Model):
    birth_year = WideYear(null=True, blank=True)
    birth_year_uncertain = models.BooleanField()
    death_year = WideYear(null=True, blank=True)
    death_year_uncertain = models.BooleanField()
    flourit_year = WideYear(null=True, blank=True)
    flourit_year_uncertain = models.BooleanField()
    FLOURIT_CHOICES = (
        (u'D', u'Birth and death dates'),
        (u'F', u'Flourit date'),
    )
    use_flourit = models.CharField('Date(s) to use', max_length=2, choices=FLOURIT_CHOICES)
    def __unicode__(self):
        if self.personname_set.filter(default_name__exact=True):
            name = z(self.personname_set.filter(default_name__exact=True)[0])
        else:
            name = u'[Unnamed person]'
        if self.use_flourit == u'D':
            dates = '%s - %s' % (z(self.birth_year), z(self.death_year))
        else:
            dates = 'fl. %s' % (z(self.flourit_year))
        return '%s (%s)' % (name, dates)
    class Meta:
        ordering = ['ordering_string']

class PersonName(models.Model):
    titles = models.CharField(max_length=65535, null=True, blank=True)
    surname = models.CharField(max_length=255, null=True, blank=True)
    first_name = models.CharField(max_length=255, null=True, blank=True)
    middle_names = models.CharField(max_length=255, null=True, blank=True)
    post_nominals = models.CharField(max_length=65535, null=True, blank=True)
    default_name = models.BooleanField()
    person = models.ForeignKey(Person, null=True, blank=True)
    def __unicode__(self):
        return '%s, %s %s' % (self.surname, self.first_name, self.middle_names)
    class Meta:
        unique_together = ("titles", "surname", "first_name", "middle_names", "post_nominals", "person")
        unique_together = ("default_name", "person")
post_save.connect(post_save_person_and_person_name, sender=PersonName)

I want PersonName to be editable inline with Person in the admin as a TabularInline. Also, I want the default_name field of PersonName to display as a radio button, such that only one PersonName per Person can have default_name=True.

It's that last part that's the hard bit. Having a radio button interface within a form is relatively easy in Django. Having one that selects, essentially, one form in a formset, appears to be much, much harder.

One way to do this would be to add JavaScript to the change_form.html for Person that uses a regex to match the <input> elements for default_name and ensures that checking one of them unchecks the rest. But this seems as though it might become broken if Django's convention for naming HTML form fields changes.

Any better ideas gratefully received!

UPDATE 17/9/2009

The following admin template extension (based on this and this) works, but it's pretty gnarly. Refinements welcomed!

{% extends "admin/change_form.html" %}

{% block extrahead %}
    <script src="/site_media/jquery-1.3.2.min.js" type="text/javascript"></script>
    <script type="text/javascript">
        jQuery(document).ready(function(){
            // Replace default_name checkboxes with radio buttons.
            $(".default_name input").each(function(){
                var name = $(this).attr('name'); // grab name of original
                var id = $(this).attr('id'); // grab id of original
                if ($(this).attr('checked')) { // grab checked value of original
                    var checked = ' checked="checked"';
                } else {
                    var checked = '';
                }
                /* create new visible input */
                var html = '<input type="radio" name="'+name+'" id="'+id+'" value="True"'+checked+' />';
                $(this).after(html).remove(); // add new, then remove original input
            });
            // Ensure only one default_name radio button can be checked at a time.
            $(".default_name input").click(function(){
                $(".default_name input").not(this).removeAttr("checked");
            });
        });
    </script>
{% endblock %}