We used to water the plants the day before packing to allow water to drain.
You could apply an anti-transpirant, but I am generally not in favor of using these.
Plants need to be packed tightly to prevent movement.
Make sure the boxes have sufficient air spaces and the boxes are protected from direct sun and heat. If possible refrigerate at about 10-12 degrees C
Movement during transport, from a bad road will result in root damage. The truck driver will have to go quite slowly - depending on the condition of the road.