Here are a few other things I would check:
1. turn on all lights, including LEDs on any awnings.
2. run the awnings out and back in a couple times.
3. open and turn on any fantastic ceiling fans/vents.
4. test the operation of the stove top plus ignite the oven.
5. if the temperature is cool enough try to get the furnace to come on and run for at least 5 minutes.
6. run all a/c units, first on cool, wait 5 or 10 minutes then switch them to heat pump and run them for a couple minutes.
7. check all operations of the frig (ice maker if it has one, cooling, etc.)
8. tires, are they G rated, if so what psi are they set at (should be at least 100psi). Check for uneven wear or any type of damage.
9. crawl under and check psi of mounted spare (should have one).
10. ask for paperwork of when the wheel bearings were either greased or repacked.
11. test the selector switch in the wet bay to make sure it works (fill the fresh water tank).
12. set the wet bay selector switch to dry camp and test the water pump (if it keeps running with no tap open there is a leak).
13. use a water hose and spray the outside down like you would if you were washing it, then go inside and see if any windows leaked.
Good luck with your purchase!