You know, I bet an old 450 Maico would be about the best bike in the world for that if you put a real big tire on the back. Right at the beginning, you see Stewart having big troubles keeping his bike balanced because it was so tall. On a track like that where you're not going very fast, the long suspension travel isn't needed, and a low seat height would help the rider stay in control and keep moving. Plus, the last thing you want in deep mud is to be bogging one second then spinning the wheel the next, and old long-stroke Maicos were famous for their smooth and torquey powerband. And, if you have it running right and use the compression-release, they're not TOO hairy to start, either. But any bike with a low height, smooth power delivery, and easy starting would be very valuable on that day.