Hey we had to do this too becuase we weren't married but we were engaged.
We did what everybody else seems to have done but also used invitations etc that people had sent us over the last year and thank you cards that were sent to us as a couple for been part of our friends wedding. Along with the usual bills, holiday tickets and a statement from each of us.
We also had our wedding booked because we wanted to get married with our family before we left, as they would be missing out on everything else in our lives, (kids etc) so We had proof from the wedding venue that we had booked been booked and he Notices of Marriage from the Registrars etc.
Just provide as much as you can and should be fine.
If i remember rightly this was after the TRA had been approved and the Visa application was lodged.
All worked out fine for us we have been in Adelaide now for 5 weeks and loving it.
Good luck with everything
Emma and James