I weigh mine empty fairly often. You'd be surprised at how much weight you can accumulate by adding a tool here, a thingamabob there. My most recent empty weight ticket is 6260, which leaves 2290 for freight.
I have hauled as much as 3000 pounds, but it's a rarity to even be offered that much, and the routing would have to be mostly flat, and I drive accordingly (slower speeds overall, and much slower accelerations). I have once carried 3000 pounds from Indiana to Vancouver, which was too much weight for the Rockies, so I had to be very careful out there, but it turned out that the extra weight made an otherwise impossible trip over some brutal snow-covered mountain passes a relative piece of cake. But generally, anything over 2000 pounds gets looked at very closely for routing, and if there's too many hills or mountains, I'll pass on the load. Fortunately, the vast majority of my loads are less-than-1000 pounds. I would guestimate that 70 percent of my loads are under 1000, 20 percent between 1000 and 1500, and 10 percent more than 1500 pounds.
Heavier loads put more wear and tear on a lot of things, like brakes, tires, bearings, suspension, all pumps, and the one that's easy to see, fuel economy. Customers rent the whole van, and some will try to fill it full, overweight if they can get away with it, but for my money, a 500 pound load will pay me more than a 2000 pound load that pays the same rate, simply by virtue of less wear and tear and better fuel economy. No, you really don't have to work harder with this thing, you can actually work smarter, instead. A reduced rate load at 100 pounds will actually pay more in realized cost savings than a regular load at 2500 pounds, in many cases.
My passenger seat has been replaced with a plywood desk with shelves where I have the CB and QC mounted, the laptop, some external hard drives and assorted junk. I have a heavy bunk, very solid, made of 1/2" wood, and there's the shelving along the rear walls made of heavy wood. There's the Microfridge (fridge/freezer/microwave) that weighs 100 pounds, and the scanner/printer. Oh, and the 260 pound house battery bank and probably 100 pounds of battery cable, lugs, busbars and class-T fuses. I carry a few tools, spare parts and oil and coolant. There is easily an extra 1000 pounds in my van between all that stuff, plus the insulation.
Curb weight of an 06 and earlier Sprinter is 4600 (3950 payload capacity). The 07's and later it's 4784 (3776 payload capacity). Sprinter Curb Weights include a full tank of fuel and a 150 pound driver. Anything else that gets added must be subtracted from the payload capacity. Some choose to use the factory decking and not add another plywood deck. Some choose to use the factory D-Rings instead of E-Track. But regardless of what you do, by the time it's outfitted for expediting, including personal items, a bunk and insulation, one can never haul as much in there as they think they can.
