Hi there,
Simplest solution for this is, Create a plugin that will add a custom fields to all the pages and posts edit/add page in wp-admin
Country Field / IP address(Wild Card)
Redirect Dropdown/Textbox to set the landing page url.
Based on the ip address and landing page selected in the above fields the plugin will redirect the use to appropriate landing page.
This will work in self host and any pages or posts created using optimize press and reusable with any theme, everything is automatic so no manual maintenance.
Let me know if you are clear and message me so that we shall discuss more in detailed,
Regards,
Ashok