I have not. When I bought my bus, I simply spoke with the shop foreman and his 2nd in command, and talked with 'em about the condition and recent work done. Told 'em my plans and asked if it would be roadworthy for a 300+ miles trip home. Also asked about the service history/records (which was provided! Rather thick folder of stuff). No 3rd party inspection was offered, or requested, or done.
My trip home, aside from a couple fuel stops, and a traffic jam, was otherwise uneventful.