Krusty - the cadets can get the 500 hours over the 5 years with RHS ICUS or even LHS ICUS. Same as Qantas cadets. The biggest limitation is the command requirement for an ATPL, of which 100 hours command must be non ICUS. Most integrated CPL courses leave you 30 hours short of that, so the real limitation is the 30 hours.
Once they meet the requirements for an ATPL and have 500 hours ICUS they can be Captains at REX.
There are many LCRPT operators in Australia who do Command Practice to get the required 500 hours ME Comm for LCRPT ops.
Airlink and Pelair (both are LCRPT) have the same issues so secondment there won't help.