Here is the website for this guy / his company -
http://en.rallypalli.is/
Actually my openion is still that sprinters are much better than e.g. E350 ON road. But definitly not as a basis for a rig like this.
Weight, braking, performance and driving onroad is very good but you can see that nothing stayed stock below the surface. So wht is really good on a sprinter for iceland conditions?
Better way is a van with a letter frame, like ford E350.
Regarding the engine: Dont get that device wrong. The stock 3l diesel with 190hp and 440NM is very powerfull and can easyly chipt to much more, Fact is that sprinter are much lighter than Ford. The engine is (probably) around 230kg vs. 450kg with the 7.3l and so is the whole Van.
Finally dont get me wrong, I would choose a Ford as basis but to make business with it you can get more benefit with Mercedes.