FWIW, I have two AC's in my trailer---a 15K unit and a 11.5K unit. We found out the last time we were out that if I park with the slide (driver side) facing West, even two AC's isn't enough to keep the temp down when in full sun. Of course, that's when it's like 102 degrees outside, like it is today. The best I was able to manage when starting out at 72 degrees in the morning was 81 by mid afternoon. We probably could have done better if I had started out at 68 degrees in the morning and oriented the camper with the slide to the East and the awning facing West.
With your unit, I'd consider moving the 13.5K unit (if that is what you have) to the bedroom area and putting a 15K unit where the 13.5K unit is now.