If we are talking about the amount of advance planning that might be involved here that is a possibility. From what I've read in the media it doesn't appear to be necessary as I haven't heard of the plates being seen on video.
I wonder how many tips LE got from Houston area residents on such a truck. I've got to imagine LE went to the dept of motor vehicles and acquired a list of all such trucks in the Houston area and maybe even Texas. There was a case in Illinois where LE had video of the vehicle the murderer was driving but couldn't read the plates. Yingying Zhang's murder. Although, LE got lucky in that there were only 18 such vehicles registered in the county and the video did show a damaged hubcap on the killer's car.
Murder of Yingying Zhang - Wikipedia
I wonder if LE has spoken to the owner of that truck already. And then there is the possibility the owner was not the killer, but someone who had access to the truck that night and the next morning. Since a body wasn't transported there wouldn't be that forensic evidence. But I wonder about blow back of blood onto the killer and then transferred onto areas of the truck.