if it was an accident why did her husband leave her body there?
I wonder if her husband even knew she was dead at the beginning. From the way the accident report states things, I don't know if this would be considered as "blaming her for her own death," but it sounds like it could be a case of "did something foolish and didn't live to tell about it."
From the accident report, it sounds like the couple could have gotten into a big tiff and he started to take off without her. So she realized that he was leaving her and grabbed onto the truck.
I thought that the engine/acceleration of the big rig when it was first taking off would have masked the "thud" or bump or whatever it sounded/felt like when she jumped and clung to the truck.
I guess that they were, for some reason, stopped on the shoulder of I-44. The next exit (where they could have stopped) is a mile or so before (going west) the accident scene. I don't know if she could have held on for that long, but I doubt I could have done it.
But it doesn't look like there are any stores or gas stations near that exit. So there's no real reason to be going there or leaving from there (Smith Hollow looks to be in BFE, MO). Also, the map I'm looking at calls I-40 "Route 66."