you say you are towing a mini digger? I assume this is not because you like to build large sand castles on your holidays but use it for work. If this is the case then any vehicles with a total train weight of 3500kkg or over require a Tachograph to be fitted to the tow vehicle and you to obey the lawas that acompany this.
So as the landy is just over 2000kg by the time you fill up with fuel, pop a couple of tools in the back, add the driver and number of pasengers then attach the trailer without the digger you find yourself very close the 3500kg limit. Add the digger and you are over and require a Tacho.