Ability to add/modify filters for OG Calendar view

I'd like to customize the OG Calendar view but it doesn't seem to be accessible via the Views module. Specifically, I'd like to add a filter by group for the calendar so I can show one or more group's calendar instead of showing them all. I can simulate this using a vocabulary that has terms corresponding to the different groups I have but this is less than satisfactory as it involves making sure to specify the correct term when creating the calendar entry and maintaing the vocabulary.

Any solutions?