You left out another possible cause of death. I believe that he's using an electrical arc welder on that gas tank, so he could also suffer death by electrocution. My theory is that he'll be electrocuted, his muscle spasms will knock out the 2x4s he's using to prop up the truck. The truck will drop forcefully, crushing the hapless welder. The fall will rupture the gas tank, so what parts of him that aren't squashed will be burned beyond recognition.