FWIW, I purchased a GE 5K BTU window A/C, just recently. I'm using it in the S&B instead of running the houses central air. It has the slinger fan and instructs to remove a plug in the condensate pan if the condensate doesn't drain correctly. Since I DIY'd a platform for the little A/C, I was able to tilt it adequately so that the water drains adequately. I can see how this may be a problem in an RV as they typically house them in a wall cabinet where the condensate may pool under/alongside the pan and water may then find it's way inside.
The fix may be to pull the unit and check level inside the cabinet housing. You could then adjust accordingly and, possibly, plumb a drain pipe to the outside so water can't fill the pan.
Good luck with your A/C, some fiddling should bring good results.