Overtime and 12-hour shifts

I work in a public hospital and our department is about to start 12-hour shifts. I am worried that with so many vacant positions, we’ll just end up doing overtime on top of the shift.
Clause 5(v)(j) of the Public Health System Nurses’ and Midwives’ (State) Award is quite clear, “no overtime shall be worked in conjunction with a 12-hour shift”. You may elect to work an overtime shift on a rostered day off but overtime by way of 
an extension to the 12-hour shift 
is a no-no.