On a DP, it's generally 2 inspections you'll be after, and anyone not willing to allow both would be an excuse to keep looking. In my experience, those qualified to inspect the chassis properly are generally not able or even willing to inspect the coach. If you find somebody able to do both, myself, I'd be leery of their capabilities to do both properly. Suggest you do whatever you can to keep it an arms length transaction by not allowing the selling dealer an opinion (that you trust) on ANYTHING (especially one who says they've never heard of this arrangement)!
In any case, if the inspector(s) find discrepancies, make sure they take a picture of each issue. This will very often be required to provide proof to a consignment seller that may be several states away, as well as a basis for determining the need/cost of the necessary repair.
Last, if you are serious about it, consider arranging for the coach part of the inspection while you are present. This will give you a chance to see and touch it first hand while it's being inspected. I would have trouble giving the first dime (that wasn't fully refundable) without seeing it in person first.
1997 37' HR Endeavor, 275hp Cat, Freightliner
03 CR-V Blue Ox, Ready Brake