As mentioned, that's a lot of heat. However, two units should hold the temp, unless you are trying to cool off an already hot trailer. One thing to check, is the "dump grill" in the bedroom unit closed? By dump grill, I mean the one that you can slide open on the cover and literally dump all the air right into the room? If it is, the air will take the path of least resistance instead of going into the ductwork. I checked our 3725 system, and with that dump closed, I could feel air movement at all the vents all the way to the other end of the trailer. Granted, it got less and less the further away from the unit. With both AC units running, there was plenty of air from all grills
That said, in our previous 3400, they found that one of the ducts had not been fully hooked up. Just dumped air into the ceiling void.
Terry and Patsy
Vietnam Veteran, US Navy
2015 GMC Sierra 4X4 3500 SRW