I would check with the city, I believe the short term rental laws apply up to 30 or 31 days. ISD is inspectional Services. When the city passed the short term rental regulations, they gave ISD some teeth to be able to enforce short term rentals.
I've heard several podcasts that interview businesses that do this exact thing, tell the landlord they are going to be doing corporate rentals or transitional housing and then just go put it up on VRBO and AIRBNB. They don't care if they pay a little more than what the current market rent is. If they cash flow several hundred bucks, and the landlord pays repairs...that's a pretty sweet little business.
There are a few folks on here that do AIRBNB from Somerville and I've heard they make 25%-50%+ more than they would just renting out the space to a yearly tenant. I have a multi here in the ville that I live in one unit and rent the others out and I want to pick my tenants/neighbors since I live in the building. That's just me though.