I see a lot of Sprinter based "C"s, all of which are diesels. Most recent models are rated for 5000 pounds, which is good enough for a Jeep Wrangler or such.
As an alternative, I might recommend a short "C" on a Ford E-450 chassis, especially if using a toad? Some models by Coachmen are rated for 8000 pounds towing, and the Ford V-10, although a thirsty engine, can easily handle almost any hills you can throw at it. The difference in price between the Ford chassis and the Sprinter can buy a lot of fuel, and even though Sprinters are decently reliable, there are a lot fewer Mercedes places that service them compared to Ford dealerships.