And apparently plenty of food and water for the trip.
Although, in the past few days, the caravan's publicists have taken to showing spot videos and interviews of the hardship of those walking all that distance. Probably, in order to be fed, the caravan has to exit the trucks, assemble, and march for an couple of hours in order to get the necessary publicity. That in itself can be tiring in the heat. But, a couple of hours isn't 24 hours of continual effort and exposure, either.
If they don't see a solid line of trucks behind this caravan to supply and feed them, then pre-positioned caches have been laid. There should be a neverending movement of supplies, think WW2's RedBall express.
And diapers and formula and porta potties and phone charging facilities and laundry and clothing and showers.
This caravan is as organic as a pack of Winstons.
Oh and lodging.