Along with adding vent covers to both vents I think the easiest fan mod for the living area vent would be a
Hengs Vortex II conversion kit. The mod does not require removing your existing vent, and the fan is multi-speed and reversible. I did this mod on our previous '96 Coachmen Catalina Class A, and it worked very well for our ventilation requirements. I was able to fish the wires for the 12VDC power by tunneling through the foam insulation with a straightened coat hanger to the near by AC duct, and then to a light fixture.