It isn't unusual for the AC pan to be tilted to one corner if the pan doesn't have a dedicated drain slot or hole located in it somewhere. The pan collects the condensate and to avoid a puddle of water sitting in the pan leading to stagnant smelly water and rust out of the pan, they are usually mounted so that one corner is low to aid in making the water run out of the pan and across the roof.
Hint- When you set your trailer up at a campsite, make the front ever so slightly higher than the back and make the curbside (the side with the door) ever so slightly higher than the street side. Even as much as a half an inch won't be noticeable inside the trailer and that will cause the water to drain off the rear, streetside corner of the trailer. No drips on your neck, no muddy areas on the "people" side of the trailer or the pass through doors on either side and if you develope black streaks, they will be predominantly in one spot.
Rooftop AC Shims
Linear Mode
