If you get the OEM running boards only the REAR MOLDED splash guards will work. On the fronts you will need NON MOLDED ones that don't wrap around the body.
In this thread you can see the factory molded splash guards on our Routan. If you then look at the accessory catalog you'll notice that the running boards go from wheel arch to wheel arch. But the rears will not interfere since they go behind the rear tire, just the fronts will interfere.
Here is an accessory catalog you can find everything you need there.