Unfortunately, I don't think there is. I was told sometime in late 2014 that in order to be common law we needed to live together and in order to live together, I needed to be a resident or student. I went with that until a few months ago when I was told by an operator on the CanadaVisa website that I can actually be sponsored and work in the US at the same time. I didn't put my name on anything as I was afraid it would potentially put me in a predicament with the Canadian government. The landlord knows I pay half and Port of entry records should show that I cross everyday but I don't think there is any physical evidence.. I doubt there are any exceptions, aside from marriage?