Keystone's "test process" is to lay a sheet of toilet paper on the vent, turn on the furnace and "if the paper moves, it's working OK".... You won't find a "balanced, equalized ducting system" in most travel trailers and the further from the furnace you get, the less air flow you'll find at any duct. That's one reason why most "popular floorplans" have the furnace located near the center of the trailer, rather than on either extreme end. It's easier to get "adequate airflow to each end "from the middle" rather than push air the "entire distance from end to end"....
So, depending on your furnace location, the ducting run length, number of duct openings along that run, you may "barely move the paper" or you may "blow it 3' into the air.....
The "key" is the answer to the question: Is the room cold or does it stay relatively warm?
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS