I saw today on the news that Death Valley reached 130 degrees today: the highest temperature seen in (I think...) over a century.
I doubt that any cover could withstand that heat for any appreciable amount of time.
Is it possible to create a suitably sized "hole", that it could be driven into, and then just use multiple tarps over the top of it?
The hole needn't be 12 feet deep: six or seven feet would suffice. It would make putting multiple tarp layers over it easier. Just leave an airspace between each tarp.