Rented a 28' V10 before from them for 3 weeks, and currently have a Class A diesel.
4K is a lot of weight as a tow for those. You need to pay close attention to the vehicles stated Gross combined capacity, and then subtract out it's actual loaded weight (coach, your belongings, people/food, fuel, water, etc), to arrive at the maximum possible tow weight. This assumes the metal in the hitch is rated at equal to or more than that tow weight.
I have seen some coaches that are close to maxed out on actual weight by themselves, which would leave little tow capacity.
You can take vehicles to a truck CAT scale, and it costs about $10 to get weighed, very simple/quick process. Four corner weigh is ideal, but at a minimum put the front axle on one pad, and the rear axle on the 2nd pad. I would suggest doing that on ANY vehicle I was contemplating purchasing. Also pay attention to the individual axle ratings, as well as tires.
As a side note, that is a lot of miles on those sale units. And if the wear and tear inside is anything like the unit we were given, they are not aging gracefully. The unit we were given turns out was low on oil (stuck out in the middle of nowhere looking for oil and thank goodness for a trucker), and tires were low on air (we ended up with a flat due to leaky valve stem). I would also look around at privately owned units, where the owner took pride in it's care.
DaveB, Raleigh, NC
2015 Tiffin RED 33AA
2014 Honda CRV