Background
I've got a website set up running WordPress. I have multiple people who need login access to manage the software. They all access the website from the same physical location, and I have access to a company intranet.
Standard Practice (?)
Normally, they would log in directly to the website, and their edits would be made to the live database.
My Goals
I want the public website to be inaccessible as much as possible. I want zero WordPress logins.
I want data duplication, in case the live server goes down.
Plan
I want to set up a two part system, with an internal copy of the website that is hosted on a company intranet, accessible only to users who are on the internal network. They will make edits there.
I am planning then to use MySQL Master-Slave replication to mirror the data from the intranet copy (Master) to the live copy (Slave), with some changes on the live copy, such as disabling user logins completely.
Question
Is this a good plan? Or is there a better option? (I am a front end dev who has been thrown into DB management, so there are probably lots of things I'm not aware of.)