Hello,
As the mounting suggested is plastic it would reduce the vibrations somewhat.
The best thing to use would be a rubber gasket in between the din rail mount and the router, which would require a longer screw than the standard one.
Our routers are vibration resistant, however, exceptionally high vibration environments could decrease the life of the device, like the engine compartment of a sailboat.
The sailboat environment also comes with high humidity and salts (if it's a sea or ocean) which could introduce corrosion of PCB components, so it would be best if the enclosure was well protected from the elements.