Engine painting while in the car?

Just had a truck here on the lift that was POR15'd They did the whole chassis years ago. You could peel it of in long strips. We just repaintes my trailer with rustoleum for the second time. It was not peeling anywhere. Just all chipped up from use. We didn't do the fenders yet they are removable and were not on. The last picture is when we first built it 6 yrs ago. The faring was not installed then