Find a local truck repair place that is familiar with the type/make of engine in the coach, and have them check it out. They may or may not be able to check the chassis as well, they're frequently a different sort of animal that may need a completely different expert opinion. Same for the coach itself.
It may help to simply think of the RV as a house. An electrical inspector may not be qualified for the plumbing, or the heater. And the problem with inspection services is just as darsben noted, they may not be qualified, and may not stand behind their report. If you decide to go that way, be SURE to check their credentials too, and ask to see a sample report. It's way too easy to have business cards printed and set yourself an expert without any foundation.
