If possible, please include if there are any notes or recollections of personal belongings in the vehicle that indicated a traveler, a camper, or a transient living out of the car.
That definitely rules out the strawberry blonde leads. I'm wondering if its the type of reddish brown that is often considered brown until the sunlight lightens it. A family might have reported the missing person as having brown hair, but spending time outdoors could have brought out the red in it. When I see the picture of the hair, I'll have a better idea of if it's worth searching for missing people with brown hair.
The makeshift campsite inspired my theory for the leads I sent via PM. That still doesn't rule out the auburn hair leads since the same choice could result in someone ending up in a situation like this.
I'm aware it's casino country and mafia is nearby. The cartel is more cut the hands and feet off than mafia. Mafia is better at disappearing bodies IMO. It could be as simple as a fight over casino winnings. At this time, I'm not trying to solve the murder. I'm trying to identify the body. Any information about his lifestyle or who he associated with might be a clue to his identity. I'm not willing to rule anything out on a feeling.
I would think off the beaten path would be ideal for dumping a body.
I'll bet there is very limited information on the car. Since it was found abandoned 5 months prior, it probably wasn't processed since there was no indication it was related to a murder at the time it was found. It was likely impounded without much inspection by LE, and auctioned or junked within a month of being towed.