Let me make a few real important points.
You don't have to change IRPA and you could achieve pretty much everything you've said. First of all, if you implement the RAD, you could, in the regulations, give the RAD the power to reopen. Let's say there was a decision. If new evidence became available or there was a passage of say a year between the decision and removal, the person would have a right to apply to the RAD in writing. It would be identical to a PRA application, right?
So you could put the regulations in place that would give RAD the power to review and reopen. The difficulty would be how you would get rid of the PRA without legislative change. You could probably do that through a regulation that would basically say that if someone's had a RAD, they wouldn't be entitled to a PRA.