Might depend on the quality of the materials in the rig. I've seen wallpaper peeling off rigs at southern RV dealers, but we do nothing to ours (we live in central Florida) and have no issues at all. Vents are usually open, though.
My advice would be to not use the a/c and keep an eye on things. If you see signs or mold or mildew, then maybe you need ventilation fans or even a/c. If not, don't worry yourself.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL