Hi Brian,
A quick overview of your requirements.
There should be a signup flow that adds user email to specific Google Group. So basically you are trying to get just emails from user. And you are not going to verify emails, activate/deactivate users, add secured section to you site, except admin panel. Am I correct?
If so then I would do it creating gateway which should wrap all Google Group specific code and just put it in 'is_valid' form case, for instance:
> GroupList.add(user_email)
where GroupList mentioned gateway.
I checked Google Settings API quickstart for python by
this link.
It seems to me that creating GroupList should very straightforward task.
Please consider my response as a suggestion only. It is just basic idea.
Regards,
Constantine C.