Mythbusters did it. Some helpful suggestions in the comments.
Ozone cleaning might do it for you.
I have an aquaintence who is in this business and they have tested their equipment on very smelly smoke filled hotel rooms and such.
I think they were very agressive with their ozone generators and got rid of the smell. In spite of the fact that this guy is in marketing, I do tend to believe him.
Ozone is very reactive and you have to make sure you don’t breathe it or you’ll cause some nasty burns, but I personally have a certain amount of trust in its ability to get rid of odors like this.
It might also damage the surfaces of your truck, but I think that would require extreme cases and very long term exposure. You might find someone in your area who can give you more information.
Human or other?
Your truck is hexed. Only a chicken sacrificed on railroad tracks can help you now. May God have mercy on your soul.
A cash bus ticket to Mexico may be in order.
Did you make the hole deep enough?
What a rude question!