I have the side mounted A/C on my '99 2619. The drain hose for the A/C is in the wheel well behind the tire on the door side of the trailer below the A/C unit. You can see it in the photo link below:
http://home.comcast.net/~trailmanor/...ell/well02.jpg
When I did my wheel well retrofit to make the wheel wells round, I had to route it through the sheet metal I added as you can see in the photo link below:
http://home.comcast.net/~trailmanor/...ell/well03.jpg
In the six years I've used the trailer I've only used the A/C three times. The first time I used it, I thought it was basically useless. But when I put an oscillating fan on the counter top over the A/C unit, I got much better results. The problem with the side mounted A/C is once it cools the space between the cabinet and the wall which only takes a few minute the compressor will shut off. With the oscillating fan the compressor will run longer and cool the trailer better.