I would use a different approach. Make a copy of your database and use your application against this copy during a QA / Pilot phase. Once you know your application is stable and doesn't introduce security or stability concerns, then you can start using your production database.
Adding a materialized view would probably be difficult to work with as you would need to inspect each updates before manually synchronizing with the master database. And since there will be significant delay between the updates and the synch you run into potential collision issues.