Thanks for the door help! I really like how yours turned out.
You asked about the Vinyl, I found it on Amazon. Now that I've looked up my order, I see it's butyl sheet. I think I went this way because it was 80 mil thick, came recommended and cost effective. Here's the link:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
They offered several varieties. This one has adhesive backing and thick foil in a quilted design. It really helps if it's warm when you put it on.
Doors: I took a short cut today, at the suggestion of my paint supplier. He figured a power washer would work to take the flaking and cracking paint off of the plastic door panels. It worked really well. The crusty black paint came off to reveal green door panels underneath. Not the right color green, but fairly nice, anyway. I washed with soap and water, then wax and grease remover and put on two coats of "SEM plastic/vinyl/fabric color coat". If this doesn't hold up, I'll clean them off and use your process to coat the panels. Pics to follow.