Mid-Bunk room cooling

[mmilburne]

I currently own a 2018 Cougar 359MBI, we have 2 AC units one for the trailer one for master bedroom. The problem Im having is the mid-bunk stays fairly warm with only having one AC vent. I opened up the wall and I see the 3" air duct coming out of the ceiling. Has anyone attached a booster air duct fan to increase the air flow? Will it hurt the other outlets due to the draw of air? Looking to cool down this room.

Thanks,
Mark