Restoring Door Panels glue? backer?

Sounds good guys. I went and bought a spray can of the 77 for $10. I like that it says you can spray it on painted surfaces, specifically hardboard. I am going to try to shake out as much powdered backing that is on the old vinyl panels. Focus my spray on the old lines that pulled up the old backerboard, spray everywhere on the new pressboard panel, and try to get it all lined up. Hey just for fun I went ahead and sprayed chrome spray on that bottom piece of plastic trim on the panel. Since all of orig chrome had peeled off. Looks good. Anyone have ideas on where to find the thick plastic vapor barrier? I dont want to buy 100ft of it.