Re: RV Inspection at Manufacturer
The more the better.
Absolutely essential is anything involved with hitching up and towing it. Suspension, tires, brakes, hookup cable, landing legs, stabilizing jacks, trailer wiring, stop lights and turn signals.
Slides, if any. Run em in and out several times, and check the seals when they are out.
If possible, check all appliances, even the ones you don't need right away (ie, both A/C and heater). Gas powered ones may be a problem, but you not only want to verify working of all water and electric fixtures, you are even more interested in spotting leaks/shorts.
General walk through to spot anything obviously wrong.
Personally, I'd try for living in it a day or 2 before leaving or even finalizing the sale. That's how we found that the toilet leaked whenever you sat on it.
It is much easier to get something fixed before you leave the lot, than after...