Depending on the unit, the condensate pan may need to accumulate a bit of water before it starts draining. With low humidity, that may take a while. One unit I had, older unit, had a "slinger" on the fan that used condensate water to help cool the condenser coil. My current units don't have that.
There's no "method" of water disposal on my current campers. I raise the camper slightly to make the water run off the roof in the direction I prefer. It can be really irritating when it makes a mud hole right at the door.
Joe and Evelyn