The n, no, off thing is just sad. It's a 100% avoidable issue. But whoever put that into spec was just so clever that they overflew and became stupid.
IMO anything other than the basic types supported by JSON (number, true, false, null) ought to be be parsed as a string. Or if you really insist, some kind of special syntax to make it clear it's not a string would probably be acceptable.
fastest_mile: 2:54
Not saying it's a good idea, mind you, but at least it's an ethos.