Maybe "Roger" had somebody else in the van and they were going somewhere to party in the van and lost control of the van. After the wreck the other person awakes up realize he's been brainwashed so takes off and never returns to camp.
I'm just throwing this out there, maybe some others think there was somebody else in the van with "Roger".

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Standing in the ocean with the sun burning low in the west
Like a fire in the cavernous darkness at the heart of the beast
With my beliefs and possessions, stopped at the frontier in my chest
At the edge of my country, my back to the sea, looking east