I have a window air conditioner that I mount in a back bedroom window when we are camping with hookups during very hot weather. I only have 30-amp service so I can only run one of the roof air conditioners when I'm hooked up to power. I decided that it wasn't worth re-wiring the coach to run them both. In combination with the front air conditioner I can easily keep the coach at a comfortable 70-75 even when it's 105 outdoors. I bought it from someone off Craigslist for about $50. I have a mount that it sits on and an insulated frame that covers the window opening around it. I plug it in separately to the pedestal. It works very well for the family and keeps the coach at a much more comfortable temp than running just one of the roof units.
Miles