I live ten miles from the accident site. I frequently drive in to the airport at o'dark thirty. I don't believe there was much traffic on the I-20/59 interstates at that hour. Not saying it couldn't happen, but...
I'm more interested in my brother-in-law's account: He drove to work at an auto shop about 5 miles from the accident, about a half-hour later (5:30). He says the ditches were filling up with fog....
He probably mentioned as well that there were scattered thunderstorms the evening before (at least down here by Vulcan) and drizzle all the next day--thus at least a certain amount of moisture in the air. As you know much better than I, the dewpoint has not dipped much below 70 this month and so although the METAR seemed to look pretty decent at the time of the accident, I would not be surprised in the slightest if there had been patchy fog in some areas.