It is probably not strictly kosher but will prevent a host of minor infringements recording driving without card on numerous driver cards and having to account for missing mileage, so probably the easiest is to get the first driver to select out of scope in the vehicle, and then leave the vehicle on that all day unless someone needs to go on the road. That person then inserts his card and the tacho automatically reverts to normal operation. You could get someone to do a vehicle print out at the end of the day if you wish.