07 Coachmen Cross Country interior light cover ???

Sounds like they direct sourced them straight from China, pre-recession. Most likely not even in business any more. I think you're SOL.

I looked up that company, found a street address in Zeeland MI. Zoomed in on G earth and the name on the sign is a different company.

I'd buy a new LED fixture that is large enough to cover the footprint and be done with it