I do remember the (minor) trench down there in what I kind of always thought of as turn one (even though Langhorne was really one big turn). The picture in the first post of this thread does make it look like folks in the infield were standing right next to the cars, at the same level as they raced by. As you said, centrifical force pushed most to the outside, but I have seen video of cars ending up in the gully between the track and the wire fence that separated the infield spectators, so no doubt, some ended up closer to the infield spectators than planned.
Anything is possible at a racetrack. Seems to me I remmber a stock car in one of the videos ending up right along the inside wire fence where it was being filmed from.
Here's a few more:
Photo By Bob Williams - Provided by Larry Jendras Jr.
Photo By Jim Simmons - Provide to The Vault by Mike Shaub.