My fifth wheel has TWO foam cut-in tracks from one end of the trailer to the other lined up on our centered roof mounted air conditioner. Not much we can do with changing any of our foam ducts.
I'm sure the trailer engineering group had a positive air pressure spec to follow for their particular air conditioner to allow all of the opened vents to provide equal air flow as much as possible..
fortunate for us our ceiling mounted vents which are mounted about every six feet along the ceiling all are push to open/close types.
I have also seen some vent covers in LOWES that you might modify to close off your open vents??? Something like these shown here
Perhaps you can contact your tailer manf and see if they have some info for you.
Roy Ken
