@Chantal713I hear your concern! I've set my listing up as available for only 28 days max, as I'm concerned about this as well.
I'd suggest that you chat with your potential guest to come to a solution that you're both comfortable with. You could preface the convo with something along the lines of, "In order to stay within the LTB guidelines of what constitutes a "short-term rental", could we set your stays up as XXX (2x2week stay)"?
I'm sure that the guest doesn't want to suddenly be on the hook as a full-time tenant either...
Be aware, too, of the differences in Airbnb policy for long term rental vs. short term, too. I'm not sure whether the "long term" ABB policy kicks in with 30+ days, or what, but have a look to make sure that whatever you set up with your guest matches what policy you want to fall under with ABB.
I haven't actually had to go through these steps myself, so can't give in depth advice - hopefully another host who has had experience with this will chime in...