You should be teaching spiral descent recovery. Also I teach 45 degree aob turns and then teach then 60 degree aob turns. It shows them then that 45 degrees is not some mystical limit.
If they are overbanking - ie 55 in a 45 get them to roll off the bank and re-enter the turn.
You should also be demonstrating to them what happens if you do a 60 degree aob turn and don't increase the power ie stall warner goes off fairly quickly.