After you put on the plastic bag, inser a vacuum hose and it will compress the foam allowing you to slide the cover on without any stretching. We do this at stereo shops when we recover seats
Best way do head rest with the bag is use a shop vacuum it will draw in the bag and foam easily slide on cover then turn off the vacuum foam will expand
The red color of the Dodge truck don't get me wrong is it cool color and answer me this how would it look blue yellow or green or purple you know the actual Mopar colors you know think about it