If you don't graduate before CLM kicks in, then give it up.
Unless you "present" yourself as being married, you'd have to live together a very long time to be ensnared into CLM against your will. Having a kid or two would shorten that, however.
There are still places in this country where doing the paperwork and finding someone "authorized" to marry people, could be expensive and time consuming.
In the distant past, those places were not hard to find. Also in the distant past, people didn't feel right about "living in sin"...and had even stronger feelings about their neighbors, "living in sin".