I have always been of the mindset that explosives solve a lot of problems. C4 is safer - you can play football with it. I wouldn't do that with dynamite.
And btw, I think it is fucking beyond awesome that det cord burns at a rate of 5 football fields per second.
But that might be a little excessive for this project.
sh!t, I would just loosen up all the dirt on both sides with a couple lateral augers, pack a couple pounds worth of C4 in both, set the det cord, stand back 200 yards, and let her rip. Take the scattered dirt and flatten on either sides so track has a nice transition, tamp it down as needed.
Or you could just rent a Bobcat but where's the actual fun in that?
Are there still perfect lefts in front?