We bought a 323qb Forest River wildcat 5th wheel last year. Although I didn't find the issues like yours, they definitely don't do a very good job of prepping them for sale.
We had issues with finish work on kitchen cabinets and bathroom floors around our tub! Great Outdoors RV up in Greeley is a warranty center for our camper. We are having a issue on our front cap with stress cracks and fading- sorry back on topic!
Inspect water ,gas and AC system, and tires. At the Beginning and end of every season I wash and wax the unit too.