A few companies are making side mounts while others make their own rear door ... Mercedes Sprinter Van Rack & Ladder Custom roof rack and ladder
Sprinter Side Mount Ladder is made with aluminum and powder coated black.
Build Your Rack for Higher Roof Vans TRANSIT, PROMASTER, SPRINTER AND
110.25" H2 Cargo Ladder Van Rack For Mercedes Sprinter
36-Inch Van Running Boards, Select Dodge, Freightliner, Mercedes Sprinter 2500
Nissan NV vans; Use with 2113-0-01 Mounting Channel Kit for the Mercedes Sprinter and low-roof Nissan NV, or 2085-0-01 Mounting Channel
The Backwoods Sprinter roof rack has flexible configurations and mounts
well as all the components needed to mount the Slimline II Tray to your vehicle.
The FVC Sprinter side ladder is custom-designed to fit in the roof rails of the
Thule TracRac Van ES SILVER 2-Bar Roof Rack for Mercedes-Benz Sprinter