The good news is that your air conditioner is working well.
All air conditioners remove humidity or water content from the air.This water need to be drained out. Apparently their is a drainage problem. The drainage channels may be blocked. Your trailer may be tilted at the wrong angle. Water most of the time will like to flow downwards.
Check your water channels and see why the water is flowing to places it should not.
Another situation is that you may have open windows or doors when the air conditioner is on. This is not only wasteful, but can also cause this problem. In this case moisture come through the door or windows and condenses on the cold metal surface such as vents and diffusers. Solution for this cause is simple, just close the windows, doors or any openings.