If we later need the legal aspect for some reason then we will go sign with witnesses at the registry office. Our wedding we have now will still be our wedding to us, that is just a formality born out of necessity.
I was going to come back and say this. I think it's a good option. You can have a celebration just how you want it right now and if that legal bit helps you out sometime then get it sorted like the government owned business transaction that it is