The OP asked about servicing the newest Sprinter engines. For service under warranty you are stuck with Mercedes and (probably) Freightliner dealers. A search of the internet should give you a list of dealers in the US. When Sprinters were sold by Dodge, there was a phone number to call for emergency service on the road and they would arrange to tow the vehicle to the nearest facility. Check with Mercedes to see how they will handle breakdowns.
The only limp-home situation we encountered with our 2006 model was a failure of the turbo resonator. I had purchased the Riordan aluminum aftermarket replacement as insurance and that was the last turbo resonator problem that we had.