How about something like:
Sol3/CA/Toronto
I'd also like all 50 state capitols (and possibly also their largest city) to exist as E.G.
Sol3/US/WA-Olympia and Sol3/US/WA-Seattle (respectively to the above; I don't know Canadian provinces that well)
Sol3 is a prefix for the 3rd planet (starting ordinal 1, but anything in the orbit of Sol can be Sol0) in our solar system. It's also nicely short so easy to type out in command lines.
Every state _should_ have it's own TZ file, even if it's just an alias. That's a good forward compatible way of allowing the same config to work if future legislative efforts produce or remove timezones. It would also allow E.G. Arizona's non DST timezone to remain correctly configured in some future where the US finally ends the nightmare of DST forever.