Cardbox will do fine as long it is not a hot day. Make plenty of holes for vents. Spread a bit of bedding. Give each bird a big slice or cut the apple in three sections and put one in each box.
That is what we do for shipping and they will be fine for five hours of driving. If you happen to get caught in traffic in the 6th hour, stop, and give him a cup of water for them to drink out of, making sure they are drinking and once they had enough, you can close the box up and continue. You can put a bit of Pedialyte in their drinking water.
In the day beforehand, give them plenty of stuff to eat and drink. About a week before traveling, get some Pedialyte dilution in their waterer.
They will be just fine.