This might be too difficult for a referendum. The BC referendum would have passed if the bar had not bee set so high, and the question(s) asked so complex. 

We probably don't need more MP's if we go to a for of proportional representation, as backbenchers are largely just proxies for the leader. 

It might also be possible to do something about electing the Senate, if this is successful, but not before the next election. Term length and some other details also need to be resolved.