Trailers do not mind being parked like forever if necessary. Motors do not like that unless you mothball them.
In both cases you will need to repack bearings and change tires if they are parked long times but. Well all vehicles need that.
Motor homes like to be driven from time to time.
Now.. With either a class A or a Trailer of like size you get about the same MPG.. When towing.
But the towed car gets way better millage when compared to the Big Pickup for the trailer.. Way better. also easier to park and nicer ride when you go to town for dinner/shopping/church/whatever.
Finally I'm singing Born to be Wild (Heading down the highway) and it's raining cats and canines...... I feel the urge to "Rest" (Pull off in a rest area) IN my calss A I'm not getting wet. The poor guy with the trailer.. SOAKED.