Event reminder on repeated date for OG

My case:
- I want to send reminders x days before every occurring date of a repeating event,
- in the restricted context of an OG group

I tried or thought about the following:
- Signup + Event Repeat
much too constraining because it implies a complex setup for the user and does not allow subsequent modification of a sequence or exceptions like date repeat field.
- Rules + VBO
seems even more complex to use than coding in PHP directly. The trick is about creating reminders for every user of a specified group for every date. One view can only return (node view) dates, nid and gid or (user view) the list of users for a given group, not guessing from nid. Setting multiple ruleset/VBO interactions is much beyond average Drupaler's capabilities.
- using notifications to fire the reminder by resaving the node x days before every occuring date
Not that less complex

I am very surprised that there is no solution for such very trivial feature (sending birthday reminder for example) is readily available
This seems an age old issue, I found many posts on this, but nothing I consider a workable solution: everything is too complex, and never addressing the restriction of an OG group context

I would really appreciate any help or indication to address this in a way accessible to non-geek Drupalers.
Thanks in advance