So yes, this is an easy mod for the X19H although it will be below the wall rather than through the wall. His GH walls come down considerably below the frame rails allowing the neat door.
The picture shows it installed with zip ties. This was only for the first couple of trips until I was satisfied with the location and operation. It is now held in place with galvanized metal strapping bolted around the frame rails (although the zip ties are still there too in case a strap fails).
This location is great as it is only a few inches away from the sewer outlet, very easy to slide the hose in and out and attach.