I have not personally faced this issue, but I have seen others rent their home on a "monthly" basis due to a lack of a rental permit that allows for shorter-term rentals.  It appears that they do enter into a 30 day contract with the primary "renter", but the contracted renter may or may not stay the entire 30 days.  Some of "monthly" renters in turn work it out with their friends or other family to use the other weeks, etc.  Not entirely legal, but I know that it is done.  Or, you could just play dumb until someone complains, if there are no penalties.