Have you checked campgrounds in the area where you want to stay? Summer rates could be very high in the Philly area.
Check tire codes for year of manufacture. Anything over 7 yrs old is a danger.
As stated above, make sure all appliances are in working order. Some water heaters need to be turned on from the outside and that is a pain. If the unit was lived in by a fulltimer or used extensively, then it could be worn out by now. Hard to tell is so unless a careful examination is done by a knowledgeable person. Make sure you drive it and check the brakes, belts, oil pressure, etc.
We had a 30ft Flair bought new in 1995. It will be cramped, but doable.
I think the asking price is quite high and would not pay anything close to 9K for the unit. JMHO
2008 40ft Tiffin Allegro Bus
2014 Honda CR-V AWD