I have deployed twice to Afghanistan. [Details deleted, for OPSEC.] I am sure that you realize this and I hope you will share this with your readers. Waiting months after TEOTWAWKI to drive to your retreat is more than foolish, it is suicidal. Anyone driving post-event without an armored vehicle (or with one, just look at the ambush scenes from "Patriots") will take casualties. Every day in Afghanistan uneducated people with limited training successfully ambush and kill highly trained military personnel driving heavily armed and armored vehicles. Now imagine an ambush that has had months to be perfected, probably through trial and error, where the ambushers are equally equipped [as you]. if not better equipped. Under these circumstances the convoy would simply have no chance. Very Best Regards, - Mike A.

Good Day, Mister Rawles,
Thank you as always for the good work you do. Regarding a late convoy out of Dodge I have this to add. I can only imagine that if you have to stop for a tyre change then you will become powerful goblin magnet. Needless to say it will not be a good time to be breaking rusty wheel bolts free with an old tyre iron. Thusly it's imperative that your wheels have been previously removed and meticulously reinstalled prior to your leaving. Your spares (yes, plural per vehicle) should be mounted to the outside of your vehicles. On a roof rack or tailgate would be the traditional approach.
The previously mentioned  maintenance vehicle running second to last in the pack will want to be equipped with a professional grade jack capable of lifting both the highest and lowest cars in your convoy, and a well charged cordless impact driver with spare batteries and labeled sockets for each vehicle is imperative.
You want to to be thinking NASCAR pit crew, not roadside assist. Any observers will have less time to organise and will also determine that you're going to be a tougher nut to crack than the usual TEOTWAWKI tourists.