FWIW, we have a 40' class A. We have two A/C units. Both are ceiling ducted, with the duct running from front to back. Typically, we run the rear A/C unit during the day to primarily cool the front where we spend our time. At night, we run the front A/C to cool the bedroom. There are several vents along the length of the duct and we close them or open them as need arises. The huge advantage is that we cool the area where we are but it is very quiet where we are. In a C, the single A/C unit is typically pumping out the cool right above your head, in a noisy way. Try it and you will see what I mean.