To answer a question above, apparently there is a National Recreational Vehicle Inspectors Association (NRVIA) that certifies inspectors.
From the web:
The National Recreational Vehicle Inspectors Association (NRVIA) is a membership organization providing certification and credentials for professional recreational vehicle inspectors across North America. NRVIA's mission is to provide credibility through the testing and awarding of credentials to qualified inspectors. Mar 22, 2016
This was the company I used:
https://www.rvqualityinspections.com/