There a a small number about. Generally the furniture is behind the cab seats. Some owners sacrifice using one of the doors and install a standard set up running along one side though.
Then you could fit furniture from the tailgate up to the 'C' pillar and still use the slider if you wanted. Obviously fitting furniture behind a cab seat would prevent the operation of the swivel base anywhere beyond 90 degrees rotation.
there is a company that convert hyundai vans that are twin sliders,the units run under the windows as normal and the slider allows access to the back of the units for maintenance etc,can't think of the name of the company,they are fairly new to the market was looking at them at the camping show at the 'excel' in london