Guess I'm surprised that an Ontario car would run around without the plate. The probability of carburetor icing would seem likely between October and April. I keep my plates on all the time. Reason being: why introduce all the dust, dirt, water, and all the other contaminants directly at the air cleaner?
If you really want to stretch a point, one could argue the benefits of cold air induction etc by leaving the plate off. If you do put on the plate, be sure to put on the appropriate decal that says: "Remove Cover For Summer Operation". That way when your hood is open at a cruise night or whatever during the summer, Joe Six Pak can show his girl friend how savvy he is because you didn't remove the cover in the summer. He just became an instant automotive expert!
Trivia: Were you aware that Ford built a prototype hood for the '57 without the hood scoop? The lower profile carb and aircleaner precluded the necessity for the hood hump.
It really looked nice. Apparently they felt saving the tooling costs by using the '55-'56 hood was the deciding factor.
Tom D.