Yes, rear tire loading on launch can exceed the total weight of the car. Unfortunately, this lasts for only a few milliseconds and...to make matters worse...is preceded by a few milliseconds of decreased loading.
An extreme example would be a car with severe squat and very low rate springs at the front. The rear of the car goes down and the front pops up. In other words, the whole car is pitching (rotating). At the beginning of this pitch motion, the rotating inertia of the car in pitch is overcome by a moment generated through the front and rear tire patches. This moment is opposite in direction to that associated with weight transfer and is therefore "hurting" performance. As the car's pitch approaches its extreme position (maximum squat and maximum front end rise), the car's angular velocity must be brought to zero. The inertia again comes into play, but, this time, the moment is in a direction favorable to rear tire loading and it is at this time that it is possible for rear tire loading to exceed the total weight of the car. Again, we're talking milliseconds for this "extra" loading. (Typical pitch inertia for a 3000 pound car is 6.5 million pounds mass inches squared.)
And, a bit of history on that NHRA crankshaft height rule: Although I can't prove it, I don't...for a minute...swallow the "safety" excuse. As you old timers might recall, it was the Ramchargers' C/A that started the "higher is better" theme. (This was due to the poor slicks available at the time and is certainly unwarranted today.) The car became so dominant in its class that, when they showed up at a strip, the Chevy-powered cars would often not run as a way of protest, claiming that it wasn't fair that they should have to run against a "factory" car. This didn't make the strip owners very happy, as they had probably featured the presence of the Ramchargers in their ads. Anyway, I don't know if it was pressure from the strip owners or from GM, but, at the same time this "safety" rule was passed, another change was made to lower the pounds per cubic inch number for C/A which, of course, allowed the Ramchargers' records to be taken by GM-powered cars.