Staying in Montreal for a week in March with a car. Don't want to pay the $25-30 daily parking fee at the Hyatt Regency. My idea, since the hotel is right on the green line, is to park at a commuter lot, like at the end of the green line, and just go out to get the car whenever I need it.

For various reasons I need the car the whole week, but want to park it for free. Is this a viable option to do that?