SOR sells molded wheel arch covers in both carpet and vinyl. A little pricey, but very good quality and fit perfectly. I have the older carpet ones on mine and they've held up well; They didn't offer the vinyl style when I bought mine.
https://www.sor.com/cat343b.sor
Where did you order the Butyl mat and foam, from? I need to do this (after 15 years :) )
(I bet Mark's happy this truck found such a good home and it's being documented!)