I was thinking about this last night. It was bothering me. Most truckers are good people and wouldn't hesitate to report a bad actor.
From a former truckers' perspective: After getting the mile marker from the article, I can tell you most of that area of road is wide, well maintained and smooth. I used to run that stretch of road weekly. There is an overnight truck parking area in that vicinity, too, Just west on I-40 about 2 miles up the road from where this happened. Not a rest stop, just a pull off with a couple of dumpsters. Always jammed with trucks at night. (pictures here: https://www.google.com/maps/uv?pb=!...OJv-OvrnETM_hqjvWXc3fqXRzCCndKbl5FC9s5&hl=en#
Most truck traffic on both sides would be going slower due to the hills in the area. This stretch of road is not lit at night, but if I recall proper, it is 3 lanes wide most of the way. Most slower truck traffic would be in the right lane. All of this make me think that if the driver hit someone or something, he/she probably knew it. But it also makes the proposed accident less likely as the trucks are going slower and visibility is good.
If someone pulled over to check the damage to his truck headed westbound, that would have been where he did it. (Eastbound the truck stops at exit 161 are the closest, but by then you've passed two major highway turnoffs.) Truckers would want to avoid any DOT violation at a scale. It would draw attention. So, if the impact broke the headlight, chicken light or running light, he would have shut down until dawn to avoid notice or perhaps dropped to the surface streets. Also, depending on which way he was going on the highway, I would look for DOT violations going through a scale with front end or right side damage. There aren't many scales in AR on I-40, but the eastbound one heading into Memphis is always open.
One last thing: as of the time of this incident, almost all trucks had GPS installed. It is part of a mandated automated driver logging system. If the police identify a suspect, this would be one way they could place him at the scene.
Hope this helps. (Wow, that was longer than I wanted it to be, sorry for wall o text)