Need to approve ticket replies before sending to requestors

I’m new to RT and I’m wondering how to accomplish a new task. (I do have
a working RT 3.4.5 system)

For certain queues I need to review all replies before sending them to
the requestor. In a way, it is the opposite of the Customer Service
configuration example in the RT Essentials book. In the book example, a
Customer Service Review group can look at support requests but not
modify them. Here, I need the support reps to comment (perhaps), never
reply directly to the requestor, and have a separate review group
approve and send the reply.

In my scenario, I have a group of subcontracted support reps that will
get a copy of each new ticket (by email) and will draft a reply. I need
to have an internal staff group review each draft reply, and either
approve it to be sent to the requestor, or correct the reply before
sending (and send corrected copy, perhaps, back to the support rep).
The requestor will see replies only from our company.

A variation of this scenario is to review replies created by new support
reps in training before allowing the reply to be sent to the requestor.

I have been told to assume the subcontracted support reps may not have
access to the RT web interface (they have their own proprietary system)
and RT will email copies of tickets to them, and they will reply to us
using the RT tracking ID in the email subject field.

Has anyone else tried this? How would you approach this?