Pack as light as possible, but here are some guidelines:
Here is what Handson is suggesting or what we suggested in the past,and here.
(I would not recommend air mattresses unless going to Arkansas (and even there I might be tempted to go without or buy closer to locale), but sleeping bags are a must And PLEASE NO SUITCASES especially for anyone going in the minivan. Travel as light as possible. At all sites we will be able to do laundry and there will be places to buy more things.
also remember camera, gloves, flashlights, cell phone chargers etc.