How about this... when you add/edit/delete an event at Google Calendar,
those modifications would automatically appear on gphangouts.com.
Wouldn't that be really convenient?
We have now implemented that.
1) Open Google Calendar and create an Event
2) Enter your Google+ profile url as "Where"
3) Add as guest/participant
4) Enter a description/topic
6) Click "Send" when it asks you if it shall send out the invite to the guests
Any modifications you make to the event, will automatically show up at gphangouts.com.
E.g. if you delete the event, it will also be removed from this website, just be sure to always confirm with "Send" when it
asks if the guests shall be updated.
Here is a screendump what it should look like in Google Calendar when you schedule the event,
the important parts are highlighted in yellow.
We would appreciate any feedback how it works out for you.
Here is also a brief video that describes the process, made by Talknology