I've been wrestling with that thought as well (leaking on track).....I don't think the pressure would get high enough to pop it out, because I don't have a water pump that spins at engine speed (it goes at a constant slow speed because it runs off an electric motor, and I don't let the car get too hot)...but I still have doubts.
Yeah, on second thought, on I'll probably just not race until I can pull it and fix it right....I might put in the rubber plug thing to drive around town for the next couple months.