Our policies require that custom solutions go through separate development, test, and production phases. I’m in the planning phase for implementing Portal for ArcGIS, and will need to deploy multiple instances (VMs/Windows) to comply with our policies. So, moving applications and services between phasing environments is somewhat straightforward, but how would Portal web maps be moved? Are there service definition files specific to Portal?
I would recommend taking a look at the ArcGIS Online Assistant. You can use this utility with Portal as well. It gives you the ability to copy content from one instance to another, as well as update the URL paths for your web maps.
Check into our Admin Tools for ArcGIS Online & Portal as well. What you're needing done here can be taken care of a lot easier. There are about 40+ tools wrapped into one place in a nice UI that is easy to use and will assist you with your ArcGIS Online and Portal administration.
There are also some more complex tools that solve issues for you such as Viewing an Items Dependencies, Migrating Users to an Active Directory environment (ADFS) and Cloning content from one organization to another.
I would think the Cloning Tools would be of interest to you with your setup as it will allow you to move content between your two portals automatically.
Hope this helps.