I often do sunflower seeds on long drives, and I agree that they help stay awake. Plus it's better than coffee since I don't have to stop to pee.

Try eating them one at a time! I found I was actually getting kind of a "salt burn" from having a wad of them (I took some long road trips). So instead I keep the bag open on the seat next to me, and just pluck out one seed at a time. Then just crack and separate like a bird.

I'd say a mix of coffee, seeds, podcasts, and silence would be the trick. The variety will help with wakefulness as much as the efficacy of any one activity.
(and get more sleep, obviously )