I am confused. AIUI you want to 'flagpole / soft landing' from Australia to Canada to activate your PR status then return within a short space of time. That is fine (I am planning to do this too in April, albeit from the UK). As others have said, good idea to give them the home address of a friend in Canada to send the PR card to, they can then courier it on to you in AUS.
Surely for this flagpole trip you would have bought return tickets (which BTW is absolutely fine with CBSA)?
Then when you are ready to finally 'land as a settler / to establish a residence', you can travel on whatever you like, one or two way tickets. I strongly suggest you check the price of one way vs return tickets anyway as very often (but not always) the cost of a one way ticket is more expensive than a return (if so, just don't bother using the return!).