When I designed my full roof rack I wanted to avoid the rust out of the clamping points to the rain gutter that I see all the time with other roof racks. Those clamp points always rust the gutter out. Mine is an 06 158 2500. What I did was on the bottom of the aluminum channel that meets the gutter I welded a bead the full length of the rack so the support was distributed along the entire gutter, not just at the clamp points, and then put some tubing on that bead to cushion the contact point. Also my clamps were lined with rubber gasket material from the auto parts stores so no metal contact anywhere against the paint. My rack has side and front air dams for better aerodynamics but still does cost a bit in mpg's but having that upper platform of plywood and outdoor carpet is a great space for carrying large items like surfboards, lumber, an observation deck, star gazing deck and it holds my 180 watt solar panel, an extra spare unmounted tire. A bunch of flush mounted tie downs and hooks for shade tarps. The front air dam rolls over the top of the rack and above the windshield is pop riveted to the roof metal. Before I powder coated the whole aluminum rack frame the front air dam laid down perfectly but the heat apparently warped the aluminum front air dam. No leaks with the pop rivets and if I ever want to remove the rack I would just drill them out and patch. Having the whole rack cover the entire sprinter roof creates a nice air space for cooling here in Socal and Baja and keeps the van so much cooler. I am sorry I can't post a photo but imagine the slant of the windshield extending above the glass with the air dam panel as it rolls over the top of the rack. I also angled the rack in just above the gutters so it tucked into the roof shape angle. I do lose a little top width of the rack but is much more aero rather than going up straight from the gutters. The top came out to about 5' wide. I also extended the rack a couple feet past the rear doors to create a shaded overhang and provides a way to hang various items over the rear open doors. Eco temp water heater, etc. It does take a forklift to remove this rack but powder coating it all was a great way to go. I normally don't carry much up there besides the spare tire which I tuck under the panel to angle it flat as it is mounted on the side rails of the rack with a stainless steel piano hinge so I can adjust the optimum angle when the need arises. Sorry no photos as I have not seen another like it anywhere. Aluminness is in my area but when I went there they had nothing like i had in mind. It is quite a commitment to attach the front air dam aluminum sheet metal to the van. I did add a piece of adhesive flexible edge trim so it would cushion the contact point where the air dam meets the front raised roof above the windshield. It has been almost three years no rot, rust or any other indication of deterioration anywhere. Padding any and all contact points is crucial to prevent rust, that and distributing the weight along the entire gutter rather than just at the clamp points also helps not to put the weight on just those same clamping points. If you were in my area you would be welcome to check it out. It has worked great to run some friends up to LA airport for surf trips and I have easily carried multiple board bags and 10 to 12 boards without any trouble up there. Best wishes on finding a rack to fill your needs. This one works for me. Thanks to all here who contribute for the rest of us.
. Okies, back to lurking 
