Wonder why mine would be much different than the newer models.
I don't get it. From the steps forward most of the Cyclones are almost exactly the same - except your 3612. Different bath, and bedroom slide.
My guess will be in the duct work then.
For the rest of the Cyclone 5th wheels the duct work comes out the left side of the main unit, has a 1-2 foot run and then makes a 90 degree turn to the bathroom and bedroom. Maybe since your bedroom is inline the duct is a straight run from the unit into the bedroom. That would make sense as to why yours seems to work better then most of us.
I changed our garage discharges. I blocked the discharge over the bunks and cut one in between the bunks and the overhead cabinets.
It helps, but by no means is ideal. If we needed the garage to be as cool as the rest of the unit I would consider adding another compact rooftop. Only problem with that though is those pesky bunks when they are up. I also cut in another discharge in the living room.