Create new object on ModelForm save, with values from related model

I have a ModelForm to allow the creation of new User objects via a subclass of CreateView, and I also have a UserProfile model with a "client" field, and connected to the User model. This:

# models.py
class UserProfile(TimeStampedModel):
    user = models.OneToOneField(User, unique=True)
    client = models.ForeignKey(Client)


# forms.py
class UserForm(ModelForm):
    def create_userprofile(self, user, client):
        profile = UserProfile()
        profile.user = user
        profile.client = client
        profile.save()

    class Meta:
        model = User
        fields = ('email', 'username', 'password', 'first_name', 'last_name', 'groups')


# views.py
class UserCreate(LoginRequiredMixin, CreateView):
    model = User
    template_name = 'usermanager/user_form.html'
    form_class = UserForm
    success_url = reverse_lazy('usermanager:list')

    def form_valid(self, form):
        ### Make sure a newly created user has a UserProfile.

        # some pseudo-code thrown in

        # First save the user
        result = super(UserCreate, self).form_valid(form)

        # Now that we have a user, let's create the UserProfile
        form.create_userprofile(created_user, current_user.userprofile.client)

        # Finally return the result of the parent method.
        return result

I want to be able to create a new UserProfile when the form is submitted (and is valid, of course), so I was doing it on the CreateView.form_valid() method, but I need the ID of the just created user, which at that time I don't think I have - do I?

At the same time, I need to assign to the new UserProfile the same client as the current (not the new) user has in his profile.

Any thoughts on how to achieve this?