I always prefer to have my fans push air into the canopy.
The reason why is that unless the canopy is very tightly sealed, the air will make it's way out of the canopy wherever it can.. cracks around doors, open back, etc, and IMO the primary goal is air circulation and exchange, which fans in more or less any orientation will produce.
Where it makes a difference is the fans. Fans pulling air out pull salty spray and water vapor with them, which doesn't do the fans any good. At least pushing air in, the fans are handling room air rather than the corrosive saltwater filled air.