I will be removing all the panels in the van to explore what type of insulation the factory has provided and add to that where possible. I had a 5000 btu in my VW vanagon and it kept up with the heat pretty well, the cubic feet in the Transit is not much different with the VW camper roof up, I'm hoping for the best. One thing we did on the VW is use a thermo window treatment for the front and rear windows which helped a great deal. I will post results. The transit passenger van came with dual air so I hope they insulated for that.