A smart thing for everyone to do, even if they aren’t planning on being arrested, is to make sure everyone in your car exchanges full legal names (this will help everyone find out where the police took you in the unlikely event you do get arrested), and also be sure to give everyone in your car the phone number of someone at home you’d like them to call if you find yourself arrested. Also, heck! If civil rights lawyers wish to join your caravan as legal observers, apparently that’s something that you can contact them and ask about. (They often do this sort of work pro bono).
Also, on the off chance that arrests do happen, folks should think about whether they would be ready to do jail support if that occurs. That’s where you wait outside the jail with yummy food like pie and hugs for all the people arrested once they come out. Be sure to do this in shifts because sometimes people are literally released at 3am, and after many hours in a cold jail cell with nothing to eat by gross jail food, they are likely to be super disoriented. Plus they won’t have their car and will really need someone to drive them home.