parking at John Abbott or even in Ile Perrot at the train station and walking to the boardwalk might also be a good idea, since the local parking area's are few and far between (plus the city patrols are merciless in handing out tickets)
Since I'm not far away, last year I rode my bike over with the kiddies, to save on the parking hassles......(think maybe the new bike path might be open too)