I implemented django-formtools SessionWizardView with a navbar, so I can jump between steps if I want to update existing instances.
My problem is, if I want to edit an instance I have to submit all forms, so they are valid and render_done is called.
There is no need to use FormWizard. You could split up your UpdateForms into several ones, each with a restricted set of fields to edit on the form.
There is a fields variable available in the models.UpdateView class to define which fields should be visible on the UpdateForm.
Then connect your navbar to the several UpdateViews and you are done.