Hi @Anonymous ,
i have no good idea for the geolocations as i do not know how to realistilly detect the location of the user.
But for me it sounds as if you could manage the visible tablecontent via location specific roles and tablepermissions, which are assigned to the contact (when they log in).
In the projects i did, the locationissue was usally solved by having more than one language in portals which usually means more than one LOCALE. I know, that users from australia might prefer german and would see german content if you use the loacle for diffrent content. But our clients usually accept this approach.
And you could create artificial locales like de-au for german australia which have geman content for australian users.
This is completely out of the box and works excellent.
If you have more detailed questions on this don't hesitate to ping me in this thread or directly.
Hope it helps,
Christian